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Haploid
Kinds of Haploid Terms modified by Haploid Selected AbstractsA member of the YER057c/yjgf/Uk114 family links isoleucine biosynthesis and intact mitochondria maintenance in Saccharomyces cerevisiaeGENES TO CELLS, Issue 6 2001Jong-Myong Kim Background Two paralogs, YIL051c and YER057c, in the Saccharomyces cerevisiae genome are members of the YER057c/Yigf/Uk114 family, which is highly conserved among Eubacteria, Archaea and Eukarya. Although the molecular function of this protein family is not clear, previous studies suggest that it plays a role in the regulation of metabolic pathways and cell differentiation. Results Yil051cp is 70% identical in amino acid sequence to Yer057cp, and differs in that the former is longer by 16 amino acids containing, in part, the mitochondrial targeting signal at the N-terminus of the protein. An HA-tagged protein of Yil051cp is localized strictly in mitochondria, while that of Yer057cp is found in both cytoplasm and nucleus. Disruption of YIL051c (yil051c,) resulted in severe growth retardation in glucose medium due to isoleucine auxotroph, and no growth in glycerol medium due to the loss of mitochondria. An extract prepared from yil051c, cells showed no transaminase activity for isoleucine, while that for valine or leucine was intact. Haploid yil051c, cells newly isolated from the YIL051c/yil051c, hetero-diploids gradually lost mitochondrial DNA within 24 h in the absence of, but not in the presence of, an isoleucine. Mutants either requiring leucine (leu2,112) or isoleucine-valine (bat1,, bat2,) in a YIL051c background showed no changes in mitochondrial DNA maintenance in the absence of requirements. Conclusions Based on these results, we named Yil051c as Ibm1 (Isoleucine Biosynthesis and Mitochondria maintenance1) and concluded that: (i) Ibm1p determines the specificity of isoleucine biosynthesis, probably at the transamination step, (ii) Ibm1p is required for the maintenance of mitochondrial DNA when isoleucine is deficient, and (iii) Isoleucine compensates for the lack of Ibm1p. Taken together, Ibm1p may act as a sensor for isoleucine deficiency as well as a regulator determining the specificity for branched amino acid transaminase. [source] Haploid all the way: a new style of asexuality revealed in animalsBIOESSAYS, Issue 2 2002Véronique Perrot Weeks et al(1) recently reported that they had found a species of mites where the parthenogenetic females are haploid. They show that this is caused by intracellular bacteria that turn genetic haploid males into haploid females. I discuss these findings and attempt to place these observations in evolutionary context. BioEssays 24:114,118, 2002. © 2002 Wiley Periodicals, Inc. [source] Mutagenesis of ,-tubulin cysteine residues in Saccharomyces cerevisiae: Mutation of cysteine 354 results in cold-stable microtubulesCYTOSKELETON, Issue 2 2001Mohan L. Gupta Jr. Abstract Cysteine residues play important roles in the control of tubulin function. To determine which of the six cysteine residues in ,-tubulin are critical to tubulin function, we mutated the cysteines in Saccharomyces cerevisiae ,-tubulin individually to alanine and serine residues. Of the twelve mutations, only three produced significant effects: C12S, C354A, and C354S. The C12S mutation was lethal in the haploid, but the C12A mutation had no observable phenotype. Based on interactive views of the electron crystallographic structure of tubulin, we suggest that substitution of serine for cysteine at this position has a destabilizing effect on the interaction of tubulin with the exchangeable GTP. The two C354 mutations, although not lethal, produced dramatic effects on microtubules and cellular processes that require microtubules. The C354 mutant cells had decreased growth rates, a slowed mitosis, increased resistance to benomyl, and impaired nuclear migration and spindle assembly. The C354A mutation produced a more severe phenotype than the C354S mutation: the haploid cells had chromosome segregation defects, only 50% of cells in a culture were viable, and a significant percentage of the cells were misshapened. Cytoplasmic microtubules in the C354S and C354A cells were longer than in the control strain and spindle structures appeared shorter and thicker. Both cytoplasmic and spindle microtubules in the two C354 mutants were extremely stable to cold temperature. After 24 h at 4°C, the microtubules were still present and, in fact, very long and thick tubulin polymers had formed. Evidence exists to indicate that the C354 residue in mammalian tubulin is near the colchicine binding site and the electron crystal structure of tubulin places the residue at the interface between the ,- and ,-subunits. The sulfhydryl group is situated in a polar environment, which may explain why the alanine mutation is more severe than the serine mutation. When the C12S and the two C354 mutations were made in a diploid strain, the mutated tubulin was incorporated into microtubules and the resulting heterozygotes had phenotypes that were intermediate between those of the mutated haploids and the wild-type strains. The results suggest that the C12 and C354 residues play important roles in the structure and function of tubulin. Cell Motil. Cytoskeleton 49:67,77, 2001. © 2001 Wiley-Liss, Inc. [source] Human and pig SRY 5, flanking sequences can direct reporter transgene expression to the genital ridge and to migrating neural crest cellsDEVELOPMENTAL DYNAMICS, Issue 3 2006Alexandre Boyer Abstract Mechanisms for sex determination vary greatly between animal groups, and include chromosome dosage and haploid,diploid mechanisms as seen in insects, temperature and environmental cues as seen in fish and reptiles, and gene-based mechanisms as seen in birds and mammals. In eutherian mammals, sex determination is genetic, and SRY is the Y chromosome located gene representing the dominant testes determining factor. How SRY took over this function from ancestral mechanisms is not known, nor is it known what those ancestral mechanisms were. What is known is that SRY is haploid and thus poorly protected from mutations, and consequently is poorly conserved between mammalian species. To functionally compare SRY promoter sequences, we have generated transgenic mice with fluorescent reporter genes under the control of various lengths of human and pig SRY 5, flanking sequences. Human SRY 5, flanking sequences (5 Kb) supported reporter transgene expression within the genital ridge of male embryos at the time of sex determination and also supported expression within migrating truncal neural crest cells of both male and female embryos. The 4.6 Kb of pig SRY 5, flanking sequences supported reporter transgene expression within the male genital ridge but not within the neural crest; however, 2.6 Kb and 1.6 Kb of pig SRY 5, flanking sequences retained male genital ridge expression and now supported extensive expression within cells of the neural crest in embryos of both sexes. When 2 Kb of mouse SRY 5, flanking sequences (,3 to ,1 Kb) were placed in front of the 1.6 Kb of pig SRY 5, flanking sequences and this transgene was introduced into mice, reporter transgene expression within the male genital ridge was retained but neural crest expression was lost. These observations suggest that SRY 5, flanking sequences from at least two mammalian species contain elements that can support transgene expression within cells of the migrating neural crest and that additional SRY 5, flanking sequences can extinguish this expression. Developmental Dynamics 235:623,632, 2006. © 2006 Wiley-Liss, Inc. [source] SEXUAL CONFLICT AND PROTEIN POLYMORPHISMEVOLUTION, Issue 7 2004Ralph Haygood Abstract Sexual conflict, where male and female reproductive interests differ, is probably widespread and often mediated by male or sperm proteins and female or egg proteins that bind to each other during mating or fertilization. One potential consequence is maintenance of polymorphism in these proteins, which might result in reproductive isolation between sympatric subpopulations. I investigate the conditions for polymorphism maintenance in a series of mathematical models of sexual conflict over mating or fertilization frequency. The models represent a male or sperm ligand and a female or egg receptor, and they differ in whether expression of either protein is haploid or diploid. For diploid expression, the conditions imply that patterns of dominance, which involve neither overdominance nor un-derdominance, can determine whether polymorphism is maintained. For example, suppose ligand expression is diploid, and consider ligand alleles L1 and L2 in interactions with a given receptor genotype; if L1/L1 males are fitter than L2/L2 males in these interactions, then polymorphism is more likely to be maintained when L1/L2 males more closely resemble L1/L1 males in these interactions. Such fitter-allele dominance might be typical of a ligand or its receptor due to their biochemistry, in which case polymorphism might be typical of the pair. [source] HAPLODIPLOIDY AS AN OUTCOME OF COEVOLUTION BETWEEN MALE-KILLING CYTOPLASMIC ELEMENTS AND THEIR HOSTSEVOLUTION, Issue 4 2004Benjamin B. Normark Abstract Haplodiploidy (encompassing both arrhenotoky and paternal genome elimination) could have originated from coevolution between male-killing endosymbiotic bacteria and their hosts. In insects, haplodiploidy tends to arise in lineages that rely on maternally transmitted bacteria for nutrition and that have gregarious broods in which competition between siblings may occur. When siblings compete, there is strong selection on maternally transmitted elements to kill males. I consider a hypothetical bacterial phenotype that renders male zygotes effectively haploid by preventing chromosome decondensation in male-determining sperm nuclei. By causing high male mortality, such a phenotype can be advantageous to the bacterial lineage. By eliminating paternal genes, it can also be advantageous to the host female. A simple model shows that the host female will benefit under a wide range of values for the efficiency of resource re-allocation, the efficiency of transmission, and the viability of haploid males. This hypothesis helps to explain the ecological correlates of the origins of haplodiploidy, as well as such otherwise puzzling phenomena as obligate cannibalism by male Micromalthus beetles, reversion to diploidy by aposymbiotic male stictococcid scale insects, and the bizarre genomic constitution of scale insect bacteriomes. [source] The immunosuppressive drug leflunomide affects mating-pheromone response and sporulation by different mechanisms in Saccharomyces cerevisiaeFEMS MICROBIOLOGY LETTERS, Issue 1 2000Hiro-aki Fujimura Abstract Leflunomide (LFM) is a novel anti-inflammatory and immunosuppressive drug, and inhibits the growth of cytokine-stimulated lymphoid cells in vitro. The effect of LFM on haploid and diploid cells of Saccharomyces cerevisiae was investigated to elucidate the molecular mechanism of action of the drug. Using a halo assay, LFM was shown to enhance the cell cycle arrest of haploid cells induced by mating pheromone ,-factor. LFM also inhibited sporulation of diploid cells completely. S. cerevisiae genes which were cloned to suppress the anti-proliferative effect when present in increased copy number were introduced and examined for their activity to suppress the effect of LFM. Out of them, MLF4/SSH4, was found to suppress the sporulation-inhibitory effect of LFM. However, MLF4 failed to suppress the enhancing effect of LFM on pheromone response. Thus, LFM is suggested to act on haploid and diploid cells by different mechanisms. [source] Polyploidy-Associated Genomic Instability in Arabidopsis thalianaGENESIS: THE JOURNAL OF GENETICS AND DEVELOPMENT, Issue 4 2010Yixing Wang Formation of polyploid organisms by fertilization of unreduced gametes in meiotic mutants is believed to be a common phenomenon in species evolution. However, not well understood is how species in nature generally exist as haploid and diploid organisms in a long evolutionary time while polyploidization must have repeatedly occurred via meiotic mutations. Here, we show that the ploidy increased for two consecutive generations due to unreduced but viable gametes in the Arabidopsis cyclin a1;2-2 (also named tardy asynchronousmeiosis-2) mutant, but the resultant octaploid plants produced progeny of either the same or reduced ploidy via genomic reductions during meiosis and pollen mitosis. Ploidy reductions through sexual reproduction were also observed in independently generated artificial octaploid and hexaploid Arabidopsis plants. These results demonstrate that octaploid is likely the maximal ploidy produced through sexual reproduction in Arabidopsis. The polyploidy-associated genomic instability may be a general phenomenon that constrains ploidy levels in species evolution. [source] Population dynamics and stage structure in a haploid-diploid red seaweed, Gracilaria gracilisJOURNAL OF ECOLOGY, Issue 3 2001Carolyn Engel Summary 1,Many red seaweeds are characterized by a haploid-diploid life cycle in which populations consist of dioecious haploid (gametophyte) and diploid (tetrasporophyte) individuals as well as an additional diploid zygote-derived sporangium (carposporophyte) stage. A demographic analysis of Gracilaria gracilis populations was carried out to explore and evaluate the population dynamics and stage structure of a typical haploid-diploid red seaweed. 2,Four G. gracilis populations were studied at two sites on the French coast of the Strait of Dover. Survival, reproduction and recruitment rates were measured in each population for up to 4 years. Eight two-sex stage-based population projection matrices were built to describe their demography. 3,All four populations were characterized by high survival and low recruitment rates. Population growth rates (,) were similar between populations and between years and ranged from 1.03 to 1.17. In addition, generation times were found to be as long as 42 years. 4,Sex and ploidy ratios were variable across populations and over time. Female frequencies ranged from 0.31 to 0.59 and tetrasporophyte frequencies from 0.44 to 0.63. However, in most cases, the observed population structures were not significantly different from the calculated stage distributions. 5,Eigenvalue elasticity analysis showed that , was most sensitive to changes in matrix transitions that corresponded to survival of the gametophyte and tetrasporophyte stages. In contrast, the contribution of the fertility elements to , was small. Eigenvector elasticity analysis also showed that survival elements had the greatest impact on sex and ploidy ratios. [source] Inbreeding depression by recessive deleterious genes affecting female fecundity of a haplo-diploid miteJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 4 2000Saito The effect of inbreeding on haplo-diploid organisms has been regarded as very low, because deleterious recessive genes on hemizygous (haploid) males were immediately purged generation by generation. However, we determined such recessive genes to decrease female fecundity in a population of Schizotetranychus miscanthi Saito which is known in the Acari as a subsocial species with haplo-diploidy. In mother,son inbreeding experiments, there was no depression in egg hatchability nor in the larval survival of progeny over four generations. There was, on the other hand, significant inbreeding depression in the fecundity with increasing f -value. Crosses between two lineages, one having deleterious effects on the fecundity and the other having no such effects, established during the inbreeding, revealed heterosis, and backcrosses showed that the depression was caused by deleterious recessive(s). These results strongly suggest the existence of some deleterious genes governing only the traits of adult females in wild populations of haplo-diploid organisms. [source] Quantitative Trait Loci for Panicle Layer Uniformity Identified in Doubled Haploid Lines of Rice in Two EnvironmentsJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 9 2009Liangyong Ma Abstract Uniformity of stem height in rice directly affects crop yield potential and appearance, and has become a vital index for rice improvement. In the present study, a doubled haploid (DH) population, derived from a cross between japonica rice Chunjiang 06 and indica rice TN1 was used to analyze the quantitative trait locus (QTL) for three related traits of panicle-layer-uniformity; that is, the tallest panicle height, the lowest panicle height and panicle layer disuniformity in two locations: Hangzhou (HZ) and Hainan (HN). A total of 16 QTLs for three traits distributed on eight chromosomes were detected in two different environments. Two QTLs, qTPH -4 and qTPH -8 were co-located with the QTLs for qLPH -4 and qLPH -8, which were only significant in the HZ environment, whereas the qTPH -6 and qLPH -6 located at the same interval were only significant in the HN environment. Two QTLs, qPLD -10-1 and qPLD -10-2, were closely linked to qTPH-10, and they might have been at the same locus. One QTL, qPLD -3, was detected in both environments, explaining more than 23% of the phenotypic variations. The CJ06 allele of qPLD -3 could increase the panicle layer disuniformity by 9.23 and 4.74 cm in the HZ and HN environments. Except for qPLD -3, almost all other QTLs for the same trait were detected only in one environment, indicating that these three traits were dramatically affected by environmental factors. The results may be useful for elucidation of the molecular mechanism of panicle-layer-uniformity and marker assisted breeding for super-rice. [source] A Genetic Map Constructed Using a Doubled Haploid Population Derived from Two Elite Chinese Common Wheat VarietiesJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 8 2008Kun-Pu Zhang Abstract Genetic mapping provides a powerful tool for the analysis of quantitative trait loci (QTLs) at the genomic level. Herein, we report a new genetic linkage map developed from an F1 -derived doubled haploid (DH) population of 168 lines, which was generated from the cross between two elite Chinese common wheat (Triticum aestivum L.) varieties, Huapei 3 and Yumai 57. The map contained 305 loci, represented by 283 simple sequence repeat (SSR) and 22 expressed sequence tag (EST)-SSR markers, which covered a total length of 2141.7 cM with an average distance of 7.02 cM between adjacent markers on the map. The chromosomal locations and map positions of 22 new SSR markers were determined, and were found to distribute on 14 linkage groups. Twenty SSR loci showed different chromosomal locations from those reported in other maps. Therefore, this map offers new information on the SSR markers of wheat. This genetic map provides new opportunities to detect and map QTLs controlling agronomically important traits. The unique features of this map are discussed. [source] Quantitative Trait Loci Mapping for Chlorophyll Fluorescence and Associated Traits in Wheat (Triticum aestivum)JOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 5 2007De-Long Yang Abstract Parameters of chlorophyll fluorescence kinetics (PCFKs) under drought stress condition are generally used to characterize instincts for dehydration tolerance in wheat (Triticum aestivum L.). Therefore, it is important to map quantitative trait loci (QTLs) for PCFKs in wheat genetic improvement for drought tolerance. A doubled haploid (DH) population with 150 lines, derived from a cross between two common wheat varieties, Hanxuan 10 and Lumai 14, was used to analyze the correlation between PCFKs and chlorophyll content (ChlC) and to map QTLs at the grain-filling stage under conditions of both rainfed (drought stress, DS) and well-watered (WW), respectively. QTLs for these traits were detected by QTLMapper version 1.0 based on the composite interval mapping method of the mixed-linear model. The results showed a very significant positive correlation between Fv, Fm, Fv/Fm and Fv/Fo. The correlation coefficients were generally higher under WW than under DS. Also, there was a significant or a highly significant positive correlation between Fv, Fm, Fv/Fm, Fv/Fo and ChlC. The correlation coefficients were higher in the DS group than the WW group. A total of 14 additive QTLs (nine QTLs detected under DS and five QTLs under WW) and 25 pairs of epistatic QTLs (15 pairs detected under DS and 10 pairs under WW) for PCFKs were mapped on chromosomes 6A, 7A, 1B, 3B, 4D and 7D. The contributions of additive QTLs for PCFKs to phenotype variation were from 8.40% to 72.72%. Four additive QTLs (two QTLs detected under DS and WW apiece) controlling ChlC were mapped on chromosomes 1A, 5A and 7A. The contributions of these QTLs for ChlC to phenotype variation were from 7.27% to 11.68%. Several QTL clusters were detected on chromosomes 1B, 7A and 7D, but no shared chromosomal regions for them were identified under different water regimes, indicating that these QTLs performed different expression patterns under rainfed and well-watered conditions. (Handling editor: Yong-Biao Xue) [source] WHAT DO WE KNOW ABOUT CHAROPHYTE (STREPTOPHYTA) LIFE CYCLES?,JOURNAL OF PHYCOLOGY, Issue 5 2010David Haig The charophyte algae are the closest living relatives of land plants. Their life cycles are usually characterized as haploid with zygotic meiosis. This conclusion, however, is based on a small number of observations and on theoretical assumptions about what kinds of life cycle are possible. Little is known about the life cycles of most charophytes, but unusual phenomena have been reported in comparatively well-studied taxa: Spirogyra and Sirogonium are reported to produce diploid gametes with synapsis of homologous chromosomes before fusion of gametic nuclei; Closterium ehrenbergii is reported to undergo chromosome reduction both before and after syngamy; and zygotes of Coleochaete scutata are reported to replicate their DNA to high levels before a series of reduction divisions. All of these phenomena require confirmation, as does the conventional account. [source] Three-genome mosses: complex double allopolyploid origins for triploid gametophytes in SphagnumMOLECULAR ECOLOGY, Issue 7 2009ERIC F. KARLIN Abstract This paper documents the occurrence of allotriploidy (having three differentiated genomes) in gametophytes of two Southern Hemisphere Sphagnum species (S. australe, S. falcatulum). The pattern of microsatellite alleles indicates that both species are composed of a complex of allodiploid and allotriploid gametophytes, with the latter resulting from two allopolyploidization events. No haploid (n = x) gametophytes were found for either species. The ploidal levels suggested by the pattern of microsatellite alleles were confirmed by flow cytometry and Feulgen DNA image densitometry. For both S. australe and S. falcatulum, the respective allodiploid plants (or their ancestors) are one of the parent species of the allotriploid plants. This is the first report of triploidy in Sphagnum gametophytes occurring in nature and also the first report of the presence of three differentiated genomes in any bryophyte. It is also the first report of intersectional allopolyploidy in Sphagnum, with S. australe appearing to have parental species from Sphagnum sections Rigida and Sphagnum, and S. falcatulum having parental species from Sphagnum sections Cuspidata and Subsecunda. In both species, the allotriploid cytotypes were the most prevalent cytotype on the South Island of New Zealand. The pattern of microsatellite alleles shows the presence of two genetically distinct populations of allodiploid S. australe, possibly indicating multiple origins of polyploidy for that allodiploid cytotype. Morphological evidence is also highly indicative of recurrent polyploidy in the allotriploid cytotype of S. falcatulum. Allopolyploidy has clearly played a major evolutionary role in these two Southern Hemisphere taxa. This study, in conjunction with other recent research, indicates that allopolyploidy is a common, if not the predominant, form of polyploidy in Sphagnum. [source] Lipid-induced filamentous growth in Ustilago maydisMOLECULAR MICROBIOLOGY, Issue 3 2004Jana Klose Summary The phytopathogenic fungus Ustilago maydis is obligately dependent on infection of maize to complete the sexual phase of its life cycle. Mating interactions between haploid, budding cells establish an infectious filamentous cell type that invades the host, induces large tumours and eventually forms large masses of black spores. The ability to switch from budding to filamentous growth is therefore critical for infection and completion of the life cycle, although the signals that influence the transition have not been identified from the host or the environment. We have found that growth in the presence of lipids promotes a filamentous phenotype that resembles the infectious cell type found in planta. In addition, the ability of the fungus to respond to lipids is dependent on both the cAMP signalling pathway and a Ras/MAPK pathway; these pathways are known to regulate mating, filamentous growth and pathogenesis in U. maydis. Overall, these results lead us to hypothesize that lipids may represent one of the signals that promote and maintain the filamentous growth of the fungus in the host environment. [source] The TEA/ATTS transcription factor CaTec1p regulates hyphal development and virulence in Candida albicansMOLECULAR MICROBIOLOGY, Issue 3 2000Anja Schweizer The temporal and spatial expression of stage-specific genes during morphological development of fungi and higher eukaryotes is controlled by transcription factors. In this study, we report the cloning and functional analysis of the Candida albicans TEC1 (CaTEC1) gene, a new member of the TEA/ATTS family of transcription factors that regulates C. albicans virulence. The promoters of the type 4, 5 and 6 proteinase isogenes (SAP4,6) contain repetitive TEA/ATTS consensus sequence motifs. This finding suggests a possible role for a homologue of Saccharomyces cerevisiae TEC1 during the activation of proteinase gene expression in C. albicans. CaTEC1 is predominantly expressed in the hyphal form of C. albicans. In vitro, serum-induced hyphal formation as well as evasion from M, after phagocytosis is suppressed in catec1/catec1 mutant cells. Furthermore, expression of the proteinase isogenes SAP4,6 is no longer inducible in these mutant cells. The deletion of the CaTEC1 gene attenuates virulence of C. albicans in a systemic model of murine candidiasis, although both mutant and revertant cells that were prepared from infected tissues or the vaginal mucosa grew in a hyphal morphology in vivo. CaTEC1 complements the pseudohyphal and invasive growth defect of haploid and diploid S. cerevisiae tec1/tec1 mutant cells and strongly activates the promoter of FLO11, a gene required for pseudohyphal growth. This study provides the first evidence pointing to an essential role for a member of the TEA/ATTS transcription factor family that had so far only been ascribed to function during development as a virulence regulator in microbial pathogenesis. [source] Histopathology and PR-protein markers provide insight into adult plant resistance to stripe rust of wheatMOLECULAR PLANT PATHOLOGY, Issue 2 2008JENNIFER MOLDENHAUER SUMMARY Stripe rust, caused by Puccinia striiformis f. sp. tritici, is a serious disease of wheat. The spring wheat cultivar Kariega expresses complete adult plant resistance to stripe rust, whereas Avocet S is susceptible. In former studies, quantitative trait loci (QTL) analysis of doubled haploid lines derived from a Kariega × Avocet S cross revealed two major QTL (QYr.sgi-7D and QYr.sgi-2B.1) and two minor QTL (QYr.sgi-1A and QYr.sgi-4A.1) responsible for the adult resistance of Kariega in the field. Avocet S contains none of these QTL. In the present study, stripe rust development was compared, by means of fluorescence and confocal laser scanning microscopy, in flag leaves of Kariega, Avocet S and six doubled haploid (DH) lines, containing all four, none or one QTL. Depending on the QTL present, the infection types of the DH lines ranged from resistant to fully susceptible. No differences in fungal growth were observed during the first 5 days post inoculation (dpi), whereas the mean length of the fungal colonies started to differ at 6 dpi. Interestingly, MP 51 carrying QYr.sgi-7D responded with lignification to the fungal growth without restricting it, whereas MP 35 containing QYr.sgi-2B.1 did not show lignified host tissue, but fungal growth was restricted. RT PCR experiments with sequences of pathogenesis-related (PR) proteins resulted in a slightly stronger induction of PR 1, 2 and 5, known markers for the hypersensitive reaction, and peroxidases in MP 51, whereas a second band for chitinases was detected in MP 35 only. [source] Quantitative trait loci for glucosinolate accumulation in Brassica rapa leavesNEW PHYTOLOGIST, Issue 4 2008Ping Lou Summary ,,Glucosinolates and their breakdown products have been recognized for their effects on plant defense, human health, flavor and taste of cruciferous vegetables. Despite this importance, little is known about the regulation of the biosynthesis and degradation in Brassica rapa. ,,Here, the identification of quantitative trait loci (QTL) for glucosinolate accumulation in B. rapa leaves in two novel segregating double haploid (DH) populations is reported: DH38, derived from a cross between yellow sarson R500 and pak choi variety HK Naibaicai; and DH30, from a cross between yellow sarson R500 and Kairyou Hakata, a Japanese vegetable turnip variety. ,,An integrated map of 1068 cM with 10 linkage groups, assigned to the international agreed nomenclature, is developed based on the two individual DH maps with the common parent using amplified fragment length polymorphism (AFLP) and single sequence repeat (SSR) markers. Eight different glucosinolate compounds were detected in parents and F1s of the DH populations and found to segregate quantitatively in the DH populations. QTL analysis identified 16 loci controlling aliphatic glucosinolate accumulation, three loci controlling total indolic glucosinolate concentration and three loci regulating aromatic glucosinolate concentrations. ,,Both comparative genomic analyses based on Arabidopsis,Brassica rapa synteny and mapping of candidate orthologous genes in B. rapa allowed the selection of genes involved in the glucosinolate biosynthesis pathway that may account for the identified QTL. [source] Seasonal and spatial patterns of population density in the marine macroalga Mazzaella splendens (Gigartinales, Rhodophyta)PHYCOLOGICAL RESEARCH, Issue 1 2006Leonard James Dyck SUMMARY Insight into demographic processes that operate at larger spatial scales can be achieved through studying local populations when a particular species of interest is examined over time, by many investigators, in a variety of locations. On the west coast of North America, Mazzaella splendens (Setchell et Gardner) Fredericq is such a species of interest. A synthesis of local demographic studies of M. splendens from the late 1960s to the present reveals a pattern that is potentially common to the larger natural populations. This is the pattern: population density is high in summer and low in winter for both alternate free-living life history phases of M. splendens. The magnitude of this seasonal change decreases in increasingly wave-exposed habitats. In wave-sheltered habitats there is a seasonal alternation from summer haploid to winter diploid dominance. This alternation gradually changes to constant diploid dominance as wave exposure in the habitat increases. Changes in population density are primarily a function of appearances and disappearances of perennating basal crusts (genets), as modules are produced or lost, rather than differential module production by genets of one phase over those of the other. To test the generality of this pattern, we examined seasonal changes in density, in local populations of M. splendens, in both a wave-sheltered and a wave-exposed habitat at Second Beach, Barkley Sound. Greater seasonal fluctuation in population density at wave-sheltered, compared to wave-exposed habitats is supported as a pattern potentially common to the natural populations of M. splendens. A change from summer haploid dominance in wave-sheltered areas to summer diploid dominance in wave-exposed areas is similarly supported. All changes in population density were the result of appearances and disappearances of genets rather than differential module production by haploid versus diploid basal crusts, also consistent with previous observations. A seasonal alternation in phase dominance, however, was absent from the wave-sheltered site at Second Beach, Barkley Sound for 3 consecutive years. Seasonal alternation in phase dominance of M. splendens appears dependent on local conditions and is not common to all natural populations. [source] How microspores transform into haploid embryos: changes associated with embryogenesis induction and microspore-derived embryogenesisPHYSIOLOGIA PLANTARUM, Issue 1 2008José M. Seguí-Simarro Microspore embryogenesis is the most powerful androgenic pathway to produce haploid and doubled haploid plants. To deviate a microspore toward embryogenesis, a number of factors, different for each species, must concur at the same time and place. Once induced, the microspore undergoes numerous changes at different levels, from overall morphology to gene expression. Induction of microspore embryogenesis not only implies the expression of an embryogenic program, but also a stress-related cellular response and a repression of the gametophytic program to revert the microspore to a totipotent status. In this review, we compile the most recent advances in the understanding of the changes undergone by the induced microspore to readapt to the new developmental scenario. We devote special attention to the efforts made to uncover changes in the transcriptome of the induced microspore and microspore-derived embryo (MDE). Finally, we discuss the influence that an in vitro environment exerts over the MDE, as compared with its zygotic counterpart. [source] Identification and inheritance of a partially dominant gene for yellow seed colour in Brassica napusPLANT BREEDING, Issue 1 2005X. P. Liu Abstract A yellow-seeded doubled haploid (DH) line no. 2127-17, derived from a resynthesized Brassica napus L., was crossed with two black-seeded Brassica cultivars ,Quantum' and ,Sprint' of spring type. The inheritance of seed colour was investigated in the F2, and BC1 populations of the two crosses and also in the DH population derived from the F1 of the cross ,Quantum'× no. 2127-17. Seed colour analysis was performed with the colorimeter CR-300 (Minolta, Japan) together with a visual classification system. The immediate F1 seeds of the reciprocals in the two crosses had the same colour as the self-pollinated seeds of the respective black- and yellow-seeded female parents, indicating the maternal control of seed colour. The F1 plants produced yellow-brown seeds that were darker in colour than the seeds of no. 2127-17, indicating the partial dominance of yellow seed over black. In the segregating BC1 progenies of the two crosses, the frequencies of the black- and yellow-seeded plants fit well with a 1 : 1 ratio. In the cross with ,Quantum', the frequencies of yellow-seeded and black-seeded plants fit with a 13 : 3 ratio in the F2 progeny, and with a 3 : 1 ratio in the DH progeny. However, a 49 : 15 segregation ratio was observed for the yellow-seeded and black-seeded plants in the F2 progeny of the cross with ,Sprint'. It was postulated from these results that seed colour was controlled by three pairs of genes. A dominant yellow-seeded gene (Y) was identified in no. 2127-17 that had epistatic effects on the two independent dominant black-seeded genes (B and C), thereby inhibiting the biosynthesis of seed coat pigments. [source] Molecular and agronomic evaluation of wheat doubled haploid lines obtained through maize pollination and anther culture methodsPLANT BREEDING, Issue 4 2003J. Guzy-Wrobelska Abstract Although maize pollination (MP) and anther culture (AC) are alternative techniques widely used for wheat doubled haploid (DH) production, there is only limited information on the attributes of the plant materials produced through both methods. This study was conducted to evaluate genetic fidelity, transmission of parental gametes, and to compare field performance of DH populations produced by the MP and AC methods from the F1s of two crosses between spring bread wheat cultivars. The DH populations were compared to single seed descent (SSD) lines created from the same crosses. In total, 76 MP and 122 AC lines of the cross between cultivars of divergent origin were subjected to RAPD and AFLP analysis. Only changes in AFLP banding patterns, at similarly low frequencies, 0.18% (MP) and 0.21% (AC), were detected. The frequency of the DH lines affected by the variation, 14.5% (MP) and 14.8% (AC), was similar in both populations. For most of the DH lines, variation in 1-2 loci only, out of several hundreds scored, was observed. A total of 14.3% (MP) and 22.2% (AC) marker loci showed the significant segregation distortion from the expected 1 : 1 ratio, but in at least one polymorphic locus the within-cultivar variation was responsible for the skewed segregation. The field performance of the corresponding MP and AC lines derived from two crosses confirmed the equivalency of both DH populations. In most of the traits analyzed, the MP and AC lines performed the same as the SSD populations created from the same crosses. No, or very small differences in means and ranges, were observed when the best 10% of the lines from all three methods were compared. Moreover, the best 10 % of the lines of the cross between Polish wheat cultivars adapted to the local environment performed significantly better for some traits than different groups of checks used in the study. [source] Development of yellow-seeded Brassica napus of double low qualityPLANT BREEDING, Issue 6 2001M. H. Rahman Abstract Two yellow-seeded white-petalled Brassica napus F7 inbred lines, developed from interspecific crosses, containing 26,28% emcic acid and more than 40 ,mol glucosinolates (GLS)/g seed were crossed with two black/dark brown seeded B. napus varieties of double low quality and 287 doubled haploid (DH) lines were produced. The segregation in the DH lines indicated that three to four gene loci are involved in the determination of seed colour, and yellow seeds are formed when all alleles in all loci are in the homozygous recessive state. A dominant gene governed white petal colour and is linked with an erucic acid allele that, in the homozygous condition, produces 26,28% erucic acid. Four gene loci are involved in the control of total GLS content where low GLS was due to the presence of recessive alleles in the homozygous condition in all loci. From the DH breeding population a yellow-seeded, yellow-petalled, zero erucic acid line was obtained. This line was further crossed with conventional B. napus varieties of double low quality and, following pedigree selection, a yellow seeded B. napus of double low quality was obtained. The yellow seeds had higher oil plus protein content and lower fibre content than black seeds. A reduction of the concentration of chromogenic substances was found in the transparent seed coat of the yellow-seeded B. napus. [source] Genetic diversity in populations of the fungi Phaeomoniella chlamydospora and Phaeoacremonium aleophilum on grapevine in FrancePLANT PATHOLOGY, Issue 1 2002B. Borie Isolates of Phaeomoniella chlamydospora (Phc) and Phaeoacremonium aleophilum (Pha), two haploid, deuteromycetous fungi, were obtained from vines showing symptoms of esca disease in different localities in two French regions, and within a single vineyard in one of these regions. The population genetic structure was determined in both fungi using random amplified polymorphic DNA (RAPD) analysis. Populations of Phc showed similar levels of diversity at local and regional levels. The most frequent Phc haplotypes were found in every population, and the frequencies of positive alleles of markers were similar across populations. The hypothesis that recombination had occurred was rejected for the full set of samples, but not for the samples reduced to haplotypes, indicating that Phc may be a recombining species. Different features were identified in Pha populations. First, the southern population of Pha appeared more diverse than the south-western populations. Second, genetic differentiation was identified between Pha populations from southern and south-western regions for several RAPDs. Finally, in the southern population of Pha no evidence for recombination was obtained, even by reducing the sample to haplotypes. Within the single vineyard surveyed, several haplotypes of both fungi were recovered and randomly distributed. Thus different infection events appeared to have occurred on a low spatial scale. Data from this study showed that haplotypes of both fungi were distributed over long distances geographically, and that most of the vineyards surveyed were infested by more than one haplotype of Phc and Pha. [source] Moderate Seasonality in Testis Function of Domestic CatREPRODUCTION IN DOMESTIC ANIMALS, Issue 5 2007S Blottner Contents Adult male domestic cats are known to produce sperm throughout the year, although sexual activity is influenced by geographical location. In the northern hemisphere, feral domestic cats reproduce usually between January and July. Thus, seasonality in testicular activity might be suggested. The aim of the present study was to investigate gametogene and endocrine activity of cat testis throughout the entire year. Testes and epididymides (n = 10,12 per month) were collected after castration. Spermatogenesis was quantified by assessment of testicular sperm per testis and by flow cytometric analysis of the cells with different DNA content. Sperm from cauda epididymis were evaluated according to motility and morphological integrity. Testicular testosterone concentration was determined by enzyme immunoassay. Testis mass and sperm production varied moderately throughout the year. Significant seasonal variations were observed in the proportion of cells in the G2/M phase of cell cycle (p = 0.004) and the meiotic transformation (ratio of haploid : tetraploid cells; p = 0.021). Changes in testicular testosterone concentration were more pronounced and showed periods with high (spring) and significantly reduced testosterone levels (autumn). A marked seasonal alteration (p < 0.001) with a peak in March was assessed in the percentage of progressively motile sperm. The proportion of morphological intact sperm was also significantly higher in spring compared with winter time (p < 0.001). In conclusion, the study suggests moderate seasonal changes in quantity of sperm, more pronounced annual variation in hormone production and a distinct seasonal influence on functional sperm parameters in domestic cat. [source] Expression of resistance to Leptosphaeria maculans in Brassica napus double haploid lines in France and Australia is influenced by locationANNALS OF APPLIED BIOLOGY, Issue 2 2008R. Delourme Abstract Blackleg, caused by Leptosphaeria maculans, is a major disease of oilseed rape (Brassica napus), worldwide, including Australia and France. The aims of these studies were first, to determine if higher levels of resistance to L. maculans could be generated in double haploid (DH) lines derived from spring-type B. napus cv. Grouse, which has a good level of field resistance to blackleg; and second, to determine whether the resistance to blackleg disease of individual DH lines responds differentially to different L. maculans field populations within and between the two countries. DH lines were extracted from cv. Grouse and tested in field experiments carried out in both France and Australia against natural L. maculans populations. Extracting and screening DH lines were an effective means to select individual lines with greatly improved expression of resistance to blackleg crown canker disease in comparison with the original parental population. However, relative disease resistance rankings for DH lines were not always consistent between sites. The higher level of resistance in France was shown to be because of a high expression level of quantitative resistance in the French growing conditions. Big differences were observed for some DH lines between the 2004 and the 2005 field sites in Australia where the L. maculans populations differed by their virulence on single dominant gene-based resistant lines derived from Brassica rapa ssp. sylvestris. This differential behaviour could not be clearly explained by the specific resistance genes until now identified in these DH lines. This investigation highlights the potential to derive DH lines with superior levels of resistance to L. maculans compared with parental populations. However, in locations with particularly high pathogen diversity, such as in southern Australia, multiyear and multisite evaluations should be performed to screen for the most efficient material in different situations. [source] Mating behaviour and alternative oviposition sites for male eggs in the heteronomous hyperparasitoid Coccophagus gurneyi Compere (Hymenoptera: Aphelinidae)AUSTRALIAN JOURNAL OF ENTOMOLOGY, Issue 1 2001GT Parkes Abstract The aphelinid parasitoid Coccophagus gurneyi Compere has unusual sex-related host relationships. Females are diploid and develop internally within mealybugs Pseudococcus calceolariae (Maskell). Males, in contrast, are haploid and hyperparasitic, developing on primary parasitoid larvae within the mealybugs. Furthermore, males have been claimed to be capable of either internal or external development, depending on the precise site of deposition of the haploid egg. This diversity of developmental pathways could indicate the existence of a sibling-species complex. We therefore quantified the mating and ovipositional behaviour of C. gurneyi, for comparison with that of an undescribed sibling species. We also checked whether the females deposit male eggs in alternative sites. The pattern of mating was found to be typical of mating behaviour in Coccophagus spp. and was consistent among all mating pairs, suggesting that the colony comprised one species. Further, the mating behaviour was significantly different from that of the undescribed sibling species. The site of male egg deposition varied and is apparently dictated by two factors; whether the mealybug is parasitised and, if so, the size of the parasitoid it contains. If the mealybugs were unparasitised or if the parasitoids within the mealybugs were small (< 0.53 mm), male eggs were deposited within the mealybug haemocoel. If the parasitoids were large (> 1.05 mm), male eggs were deposited within the parasitoids. These results support the claim of alternate host relationships and developmental pathways within males of C. gurneyi. [source] Haploid all the way: a new style of asexuality revealed in animalsBIOESSAYS, Issue 2 2002Véronique Perrot Weeks et al(1) recently reported that they had found a species of mites where the parthenogenetic females are haploid. They show that this is caused by intracellular bacteria that turn genetic haploid males into haploid females. I discuss these findings and attempt to place these observations in evolutionary context. BioEssays 24:114,118, 2002. © 2002 Wiley Periodicals, Inc. [source] Allopolyploidy and homoploid hybridization in the Sphagnum subsecundum complex (Sphagnaceae: Bryophyta)BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 1 2010MARIANA RICCA Several complexes of species in Sphagnum (peat mosses) originated through hybridization and allopolyploidy, suggesting that these processes have played a major evolutionary role in this genus. The Sphagnum subsecundum complex includes gametophytically haploid and diploid species in North America. Analyses of 12 microsatellite loci and sequences from two plastid DNA markers show that the evolutionary history of this group is substantially more complex than previously thought. Two taxonomic species, Sphagnum lescurii and Sphagnum inundatum, include both haploid and diploid populations. Within each ploidal level, S. lescurii and S. inundatum are not genetically differentiated. The diploid taxa show patterns of fixed heterozygosity for the microsatellite markers, consistent with an allopolyploid origin. Diploid S. lescurii is an allopolyploid between haploid S. lescurii and (haploid) S. subsecundum. Sphagnum carolinianum is an allopolyploid between haploid S. lescurii and an unknown parent. We detected homoploid hybridization between the haploids Sphagnum contortum and S. subsecundum. Finally, we report three samples of diploid Sphagnum platyphyllum (otherwise haploid) that have an allopolyploid origin involving north-eastern haploid S. platyphyllum and an unidentified taxon. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99, 135,151. [source] | |||||||||||||||||||||||||||||||