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Salinity Tolerance (salinity + tolerance)
Selected AbstractsGenetic Diversity and Association Analysis for Salinity Tolerance, Heading Date and Plant Height of Barley Germplasm Using Simple Sequence Repeat MarkersJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 8 2008Lilia Eleuch Abstract The objective of this study was to investigate the genetic diversity of barley accessions. Additionally, association trait analysis was conducted for grain yield under salinity, heading date and plant height. For this purpose, 48 barley genotypes were analyzed with 22 microsatellite simple sequence repeat (SSR) markers. Four of the 22 markers (Bmac316, scssr03907, HVM67 and Bmag770) were able to differentiate all barley genotypes. Cluster and principal coordinate analysis allowed a clear grouping between countries from the same region. The genotypes used in this study have been evaluated for agronomic performance in different environments. Conducting association analysis for grain yield under salinity conditions using TASSEL software revealed a close association of the marker Bmag749 (2H, bin 13) in two different environments with common significant alleles (175, 177), whereas the HVHOTR1 marker (2H, bin 3) was only significant in Sakhar_Egypt with alleles size being 158 and 161. Heading date also showed an association with scssr03907 through the common significant specific allele 111 and EBmac0415 markers in three different agro climatic locations, whereas HVCMA, scssr00103 and HVM67 were linked to heading date in the Egyptian environment only. The plant height association analysis revealed significant markers Bmag770 via the significant allele 152 and scssr09398. [source] Salinity tolerance in young Allis shad larvae (Alosa alosa L.)ECOLOGY OF FRESHWATER FISH, Issue 1 2008A. Bardonnet Abstract,,, Estuarine migration in Allis shad (Alosa alosa) usually does not take place before mid-summer, but exposure to salinity in brackish water may occur earlier as many spawning areas are of necessity located in upper estuarine zones due to the placement of dams. Therefore, Allis shad conservation programmes need to consider the risk of mortality due to the ability of young Allis shad to tolerate salinity. To evaluate larval mortality due to the inability of larvae to withstand salinity during early ontogeny, we exposed larvae of different ages (from few days old to 27 days old) to salinities ranging from 0 to 30 g·l,1. Results indicate that direct seawater exposure induces high mortality in young larvae whatever the ontogenetic stage. However, young larvae can easily deal with upper estuary salinity conditions. [source] Research note: Salinity tolerance of Arctic kelps from SpitsbergenPHYCOLOGICAL RESEARCH, Issue 4 2007Ulf Karsten SUMMARY The effect of hypo- and hypersaline treatments on the effective quantum yield of photosystem II was comparatively studied with a pulse amplitude modulated fluorometer (PAM) in the brown algal species Alaria esculenta, Fucus distichus, Laminaria digitata, Laminaria solidungula, Saccharina latissima (formerly Laminaria saccharina) and Saccorhiza dermatodea collected in the Arctic Kongsfjorden (Spitsbergen). While the euryhaline F. distichus was not affected at all by salinities ranging from 5 to 60 psu, A. esculenta, S. latissima and L. solidungula exhibited under hyposaline conditions strong loss of pigments (bleaching) or even high mortality reflecting stenohaline features. In contrast to the latter species, L. digitata and S. dermatodea survived all salinities, but showed reduced photosynthetic activities at the lowest and highest salt treatments and hence, can be characterized as stenohaline-euryhaline organisms. The data are discussed in terms of vertical zonation (eulittoral versus sublittoral habitat), in terms of interactive effects with other abiotic factors such as temperature and in terms of the species-specific acclimation potential. [source] DNA markers for estimation of inbreeding depression and heterosis in the guppy Poecilia reticulataAQUACULTURE RESEARCH, Issue 11 2003Takahito Shikano Abstract Molecular markers have significant potential for use in precise breeding programmes in aquaculture. This paper reviews the use of DNA markers to estimate inbreeding depression and heterosis in the guppy Poecilia reticulata. Full-sib matings revealed that inbreeding causes declines in survival and salinity tolerance, but not in undwarfism, growth and high water temperature tolerance, indicating the effects of inbreeding differ among fitness-related traits. Salinity tolerance was used to quantify the level of inbreeding depression and heterosis because the trait is strongly sensitive to inbreeding and shows a linear decrease with an increase in inbreeding coefficient. A positive correlation was observed between heterozygosity at microsatellite loci and salinity tolerance among 17 guppy populations. This indicates that heterozygosity estimated from microsatellites is a useful indicator for the estimation of inbreeding depression, suggesting that overall heterozygosity is important for fitness-related traits that show inbreeding depression. Use of DNA markers to estimate the amount of heterosis in various strain combinations was examined using diallele and reciprocal crosses among four domestic strains. The amount of heterosis differed among the strain combinations and correlated with Nei's genetic distance measured by microsatellites and also by dissimilarity using random amplified polymorphic DNA (RAPD) analysis. This indicates that microsatellite and RAPD markers are useful for estimating the amount of heterosis in various strain combinations, further suggesting that the amount of heterosis depends on the genetic differences between the strains. The present study showed that DNA markers are useful tools for estimating inbreeding depression and heterosis in guppy breeding. [source] Laboratory-based reproduction success of ruffe, Gymnocephalus cernuus (L.), in brackish water is determined by maternal propertiesECOLOGY OF FRESHWATER FISH, Issue 2 2006A. Albert Abstract,, Body length, age, egg size, embryo salinity tolerance and length at hatching of the freshwater (salinity <0.1 ppt, Lake Peipsi) and brackish-water (salinity 2,6 ppt, Pärnu and Matsalu Bay) ruffe, Gymnocephalus cernuus (L.), were examined to reveal their reproductive success in moderate salinity. Eggs of females originating from brackish water were significantly larger than eggs of freshwater females. No correlation between egg size and female size and age was found in brackish-water populations. In the freshwater population there was a small negative correlation between egg size and female size, but no correlation with female age. Fertilisation by sperm of males of different origin (brackish water or freshwater) produced no significant differences at any critical developmental stage (fertilisation, gastrulation, hatching) in the development of eggs from brackish-water or freshwater females at 3.3, 5.5, 7.7 and 9.9 ppt salinity. Survival rates in different salinity depended only on female origin; embryonic salinity tolerance was higher in ruffe inhabiting brackish water. Obviously, embryo salinity tolerance in ruffe is determined by egg qualities. [source] Microbial response to salinity change in Lake Chaka, a hypersaline lake on Tibetan plateauENVIRONMENTAL MICROBIOLOGY, Issue 10 2007Hongchen Jiang Summary Previous investigations of the salinity effects on the microbial community composition have largely been limited to dynamic estuaries and coastal solar salterns. In this study, the effects of salinity and mineralogy on microbial community composition was studied by using a 900-cm sediment core collected from a stable, inland hypersaline lake, Lake Chaka, on the Tibetan Plateau, north-western China. This core, spanning a time of 17 000 years, was unique in that it possessed an entire range of salinity from freshwater clays and silty sands at the bottom to gypsum and glauberite in the middle, to halite at the top. Bacterial and archaeal communities were studied along the length of this core using an integrated approach combining mineralogy and geochemistry, molecular microbiology (16S rRNA gene analysis and quantitative polymerase chain reaction), cultivation and lipid biomarker analyses. Systematic changes in microbial community composition were correlated with the salinity gradient, but not with mineralogy. Bacterial community was dominated by the Firmicutes -related environmental sequences and known species (including sulfate-reducing bacteria) in the freshwater sediments at the bottom, but by halophilic and halotolerant Betaproteobacteria and Bacteroidetes in the hypersaline sediments at the top. Succession of proteobacterial groups along the salinity gradient, typically observed in free-living bacterial communities, was not observed in the sediment-associated community. Among Archaea, the Crenarchaeota were predominant in the bottom freshwater sediments, but the halophilic Halobacteriales of the Euryarchaeota was the most important group in the hypersaline sediments. Multiple isolates were obtained along the whole length of the core, and their salinity tolerance was consistent with the geochemical conditions. Iron-reducing bacteria were isolated in the freshwater sediments, which were capable of reducing structural Fe(III) in the Fe(III)-rich clay minerals predominant in the source sediment. These data have important implications for understanding how microorganisms respond to increased salinity in stable, inland water bodies. [source] Assessment of Growth, Physiological and Biochemical Parameters and Activities of Antioxidative Enzymes in Salinity Tolerant and Sensitive Basmati Rice VarietiesJOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 6 2007M. P. Singh Abstract This investigation was undertaken to compare the level of salinity tolerance of the newly bred CSR-30 basmati rice variety with that of the salinity sensitive HBC-19 and Pokkali rice varieties. Twenty-one-day-old hydroponically raised seedlings at 6 and 12 dS m,1 were investigated for growth, photosynthetic rate, chlorophyll content, ribulose-1,5-bisphosphate carboxylase-oxygenase (Rubisco) activity, relative water content (RWC), membrane stability index (MSI), lipid peroxidation, Na/K ratio and activities and gene expression of various isoforms of antioxidative enzymes. Salinity stress led to reduction in shoot length, leaf area, dry weight, RWC, MSI, rate of photosynthesis, chlorophyll content and Rubisco activity in all the three rice varieties. The levels of reduction in these parameters were maximal in HBC-19 followed by those in CSR-30 and Pokkali respectively. Cumulative superoxide dismutase (SOD) activity increased in Pokkali and CSR-30 in consonance with increase in salinity stress while it decreased in HBC-19. The Mn-SOD activity however, was enhanced in all three varieties in the presence of salinity stress while the activities of Fe-SOD, Cu/Zn-SOD and ascorbate peroxidase were decreased in HBC-19 when compared with CSR-30 and Pokkali. The activity of catalase (CAT) was higher in HBC-19 when compared with its activity in CSR-30 and Pokkali. The levels of gene expressions of the three isoforms of SOD ascertained by reverse transcriptase polymerase chain reaction were not necessarily indicative of the activities of the corresponding enzymes. Thus, despite the maximal enhancement in gene expression of Fe-SOD in HBC-19 in response to salinity stress, the activity of this enzyme in HBC-19 remained low. Similarly, despite a marginal increase in gene expression of Cu-Zn SOD in the three varieties, its activity was significantly higher in Pokkali and CSR-30 when compared with that in HBC-19. A significant enhancement in the activity of CAT at 12 dS m,1 in HBC-19 when compared with CSR-30 and Pokkali might confer a degree of tolerance to H2O2 stress in this variety in the presence of higher levels of NaCl at the seedling stage. [source] The influence of environmental factors, the pollen : ovule ratio and seed bank persistence on molecular evolutionary rates in plantsJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 1 2006C.-A. WHITTLE Abstract One of the main goals of molecular evolutionary biology is to determine the factors that influence the evolutionary rate of selectively neutral DNA, but much remains unknown, especially for plants. Key factors that could alter the mutation rate include environmental tolerances (because they reflect a plants vulnerability to changes in habitat), the pollen : ovule ratio (as it is associated with the number of mitotic divisions) and seed longevity (because this influences the number of generations per unit time in plants). This is the first study to demonstrate that seed bank persistence and drought tolerance are positively associated with molecular evolutionary rates in plants and that pollen : ovule ratio, shade tolerance and salinity tolerance have no detectable relationship. The implications of the findings to our understanding of the impact of environmental agents, the number of cell divisions and cell aging on neutral DNA sequence evolution are discussed. [source] Adaptive evolution of baker's yeast in a dough-like environment enhances freeze and salinity toleranceMICROBIAL BIOTECHNOLOGY, Issue 2 2010Jaime Aguilera Summary We used adaptive evolution to improve freeze tolerance of industrial baker's yeast. Our hypothesis was that adaptation to low temperature is accompanied by enhanced resistance of yeast to freezing. Based on this hypothesis, yeast was propagated in a flour-free liquid dough model system, which contained sorbitol and NaCl, by successive batch refreshments maintained constantly at 12°C over at least 200 generations. Relative to the parental population, the maximal growth rate (µmax) under the restrictive conditions, increased gradually over the time course of the experiment. This increase was accompanied by enhanced freeze tolerance. However, these changes were not the consequence of genetic adaptation to low temperature, a fact that was confirmed by prolonged selection of yeast cells in YPD at 12°C. Instead, the experimental populations showed a progressive increase in NaCl tolerance. This phenotype was likely achieved at the expense of others traits, since evolved cells showed a ploidy reduction, a defect in the glucose derepression mechanism and a loss in their ability to utilize gluconeogenic carbon sources. We discuss the genetic flexibility of S. cerevisiae in terms of adaptation to the multiple constraints of the experimental design applied to drive adaptive evolution and the technologically advantageous phenotype of the evolved population. [source] Contrasting patterns in genetic diversity following multiple invasions of fresh and brackish watersMOLECULAR ECOLOGY, Issue 12 2006DAVID W. KELLY Abstract Biological invasions may combine the genetic effects of population bottlenecks and selection and thus provide valuable insight into the role of such processes during novel environmental colonizations. However, these processes are also influenced by multiple invasions, the number of individuals introduced and the degree of similarity between source and receiving habitats. The amphipod Gammarus tigrinus provides a useful model to assess these factors, as its invasion history has involved major environmental transitions. This species is native to the northwest Atlantic Ocean, although it invaded both brackish and freshwater habitats in the British Isles after introduction more than 65 years ago. It has also spread to similar habitats in Western Europe and, most recently, to Eastern Europe, the Baltic Sea, and the Laurentian Great Lakes. To examine sources of invasion and patterns of genetic change, we sampled populations from 13 native estuaries and 19 invaded sites and sequenced 542 bp of the mitochondrial COI gene. Strong native phylogeographical structure allowed us to unambiguously identify three allopatrically evolved clades (2.3,3.1% divergent) in invading populations, indicative of multiple introductions. The most divergent clades occurred in the British Isles and mainland Europe and were sourced from the St Lawrence and Chesapeake/Delaware Bay estuaries. A third clade was found in the Great Lakes and sourced to the Hudson River estuary. Despite extensive sampling, G. tigrinus did not occur in freshwater at putative source sites. Some European populations showed reduced genetic diversity consistent with bottlenecks, although selection effects cannot be excluded. The habitat distribution of clades in Europe was congruent with the known invasion history of secondary spread from the British Isles. Differences in salinity tolerance among lineages were suggested by patterns of habitat colonization by different native COI clades. Populations consisting of admixtures of the two invading clades were found principally at recently invaded fresh and brackish water sites in Eastern Europe, and were characterized by higher genetic diversity than putative source populations. Further studies are required to determine if these represent novel genotypes. Our results confirm that biological invasions need not result in diminished genetic diversity, particularly if multiple source populations, each with distinctive genetic composition, contribute to the founding populations. [source] Comparative phylogeography of Ponto-Caspian mysid crustaceans: isolation and exchange among dynamic inland sea basinsMOLECULAR ECOLOGY, Issue 10 2006ASTA AUDZIJONYTE Abstract The distributions of many endemic Ponto-Caspian brackish-water taxa are subdivided among the Black, Azov and Caspian Sea basins and further among river estuaries. Of the two alternative views to explain the distributions, the relict school has claimed Tertiary fragmentation of the once contiguous range by emerging geographical and salinity barriers, whereas the immigration view has suggested recolonization of the westerly populations from the Caspian Sea after extirpation during Late Pleistocene environmental perturbations. A study of mitochondrial (COI) phylogeography of seven mysid crustacean taxa from the genera Limnomysis and Paramysis showed that both scenarios can be valid for different species. Four taxa had distinct lineages related to the major basin subdivision, but the lineage distributions and depths of divergence were not concordant. The data do not support a hypothesis of Late Miocene (10,5 Myr) vicariance; rather, range subdivisions and dispersal from and to the Caspian Sea seem to have occurred at different times throughout the Pleistocene. For example, in Paramysis lacustris each basin had an endemic clade 2,5% diverged from the others, whereas Paramysis kessleri from the southern Caspian and the western Black Sea were nearly identical. Species-specific ecological characteristics such as vagility and salinity tolerance seem to have played important roles in shaping the phylogeographic patterns. The mitochondrial data also suggested recent, human-mediated cryptic invasions of P. lacustris and Limnomysis benedeni from the Caspian to the Sea of Azov basin via the Volga-Don canal. Cryptic species-level subdivisions were recorded in populations attributed to Paramysis baeri, and possibly in P. lacustris. [source] Systemin-dependent salinity tolerance in tomato: evidence of specific convergence of abiotic and biotic stress responsesPHYSIOLOGIA PLANTARUM, Issue 1 2010Francesco Orsini Plants have evolved complex mechanisms to perceive environmental cues and develop appropriate and coordinated responses to abiotic and biotic stresses. Considerable progress has been made towards a better understanding of the molecular mechanisms of plant response to a single stress. However, the existence of cross-tolerance to different stressors has proved to have great relevance in the control and regulation of organismal adaptation. Evidence for the involvement of the signal peptide systemin and jasmonic acid in wound-induced salt stress adaptation in tomato has been provided. To further unravel the functional link between plant responses to salt stress and mechanical damage, transgenic tomato (Lycopersicon esculentum Mill.) plants constitutively expressing the prosystemin cDNA have been exposed to a moderate salt stress. Prosystemin over-expression caused a reduction in stomatal conductance. However, in response to salt stress, prosystemin transgenic plants maintained a higher stomatal conductance compared with the wild-type control. Leaf concentrations of abscissic acid (ABA) and proline were lower in stressed transgenic plants compared with their wild-type control, implying that either the former perceived a less stressful environment or they adapted more efficiently to it. Consistently, under salt stress, transgenic plants produced a higher biomass, indicating that a constitutive activation of wound responses is advantageous in saline environment. Comparative gene expression profiling of stress-induced genes suggested that the partial stomatal closure was not mediated by ABA and/or components of the ABA signal transduction pathway. Possible cross-talks between genes involved in wounding and osmotic stress adaptation pathways in tomato are discussed. [source] Carbon isotope discrimination: potential for screening salinity tolerance in rice at the seedling stage using hydroponicsPLANT BREEDING, Issue 3 2005R. Shaheen Abstract Rice is a moderately salt-sensitive crop species and soil salinity is the single most widespread soil toxicity problem lacing rice production. The quantification of salinity resistance poses serious problems in the field because of climatic factors and field heterogeneity. In the present study. rice germplasm obtained from the International Rice Research Institute (IRRI). Philippines, was screened in a naturally lit (11 h daylight) glasshouse-based hydroponics unit at two salinity levels (4 and 6 dS/m), Phenotypic performance based on survival of tolerant, moderately tolerant and susceptible isogenic lines along with tolerant and susceptible parents was evaluated after 10 and 13 days of salt stress. Plants were harvested after second scoring and carbon isotope discrimination in the leaves (A) was measured. ,1 ranged from 19.5 to 22.9%, A highly significant negative correlation (r =,0.95. P < 0.001) between , and visual scoring was observed. Data indicated the potential of using , as a physiological indicator for salinity tolerance in rice seedlings grown in hydroponics. [source] Na+ transport in glycophytic plants: what we know and would like to knowPLANT CELL & ENVIRONMENT, Issue 4 2010DARREN CRAIG PLETT ABSTRACT Soil salinity decreases the growth rate of plants and can severely limit the productivity of crop plants. The ability to tolerate salinity stress differs widely between species of plants as well as within species. As an important component of salinity tolerance, a better understanding of the mechanisms of Na+ transport will assist in the development of plants with improved salinity tolerance and, importantly, might lead to increased yields from crop plants growing in challenging environments. This review summarizes the current understanding of the components of Na+ transport in glycophytic plants, including those at the soil to root interface, transport of Na+ to the xylem, control of Na+ loading in the stele and partitioning of the accumulated Na+ within the shoot and individual cells. Using this knowledge, strategies to modify Na+ transport and engineer plant salinity tolerance, as well as areas of research which merit particular attention in order to further improve the understanding of salinity tolerance in plants, are discussed. [source] Quantifying the three main components of salinity tolerance in cerealsPLANT CELL & ENVIRONMENT, Issue 3 2009KARTHIKA RAJENDRAN ABSTRACT Salinity stress is a major factor inhibiting cereal yield throughout the world. Tolerance to salinity stress can be considered to contain three main components: Na+ exclusion, tolerance to Na+ in the tissues and osmotic tolerance. To date, most experimental work on salinity tolerance in cereals has focused on Na+ exclusion due in part to its ease of measurement. It has become apparent, however, that Na+ exclusion is not the sole mechanism for salinity tolerance in cereals, and research needs to expand to study osmotic tolerance and tissue tolerance. Here, we develop assays for high throughput quantification of Na+ exclusion, Na+ tissue tolerance and osmotic tolerance in 12 Triticum monococcum accessions, mainly using commercially available image capture and analysis equipment. We show that different lines use different combinations of the three tolerance mechanisms to increase their total salinity tolerance, with a positive correlation observed between a plant's total salinity tolerance and the sum of its proficiency in Na+ exclusion, osmotic tolerance and tissue tolerance. The assays developed in this study can be easily adapted for other cereals and used in high throughput, forward genetic experiments to elucidate the molecular basis of these components of salinity tolerance. [source] There are High Levels of Functional and Genetic Diversity in Oxyrrhis marinaTHE JOURNAL OF EUKARYOTIC MICROBIOLOGY, Issue 3 2005CHRIS D. LOWE Abstract. Oxyrrhis marina, a widely distributed marine protist, is used to model heterotrophic flagellate responses in microbial food webs. Although clonal variability occurs in protists, assessments of intraspecific diversity are rare; such assessments are critical, particularly where species are used as models in ecological studies. To address the extent of intraspecific variation within O. marina, we assessed diversity among 11 strains using 5.8S rDNA and ITS sequences. The 5.8S rDNA and ITS regions revealed high divergence between strains: 63.1% between the most diverse. To compare O. marina diversity relative to other alveolates, 18S rDNA sequences for five strains were analysed with sequences from representatives of the major alveolate groups. 18S rDNA also revealed high divergence in O. marina. Additionally, consistent with phylogenies based on protein coding genes, maximum likelihood analysis indicated that O. marina was monophyletic and ancestral to the dinoflagellates. To assess ecophysiological differences, growth rates of seven O. marina strains were measured at 10 salinities (10,55,). Two salinity responses occurred: one group achieved highest growth rates at high salinities; the other grew best at low salinities. There was no clear correlation between molecular, ecophysiological, or geographical differences. However, salinity tolerance was associated with habitat type: intertidal strains grew best at high salinities; open-water strains grew best at low salinities. These data indicate the need to examine many strains of a species in both phylogenetic and ecological studies, especially where key-species are used to model ecological processes. [source] Dietary supplementation of mannan oligosaccharide on white sea bream (Diplodus sargus L.) larvae: effects on development, gut morphology and salinity toleranceAQUACULTURE RESEARCH, Issue 9 2010Arkadios Dimitroglou Abstract The influence of dietary mannan oligosaccharide (MOS) on the development, gut integrity and quality (in respect of stamina and survivability) of white sea bream Diplodus sargus L. larvae was investigated. White sea bream larvae were held under appropriate rearing conditions and fed Artemia, enriched by A1 DHA SelcoŌ with the addition or absence of MOS (Bio-Mos®). The results indicated that larval growth performance and survivability were not affected by the MOS supplementation. Light microscopy revealed that MOS supplementation significantly improved the intestinal morphology by increasing the villi surface area by over 12%. Transmission electron microscopy revealed that MOS supplementation increased the microvilli length by 26% compared with the control. Salinity challenge experiments showed that MOS significantly increased larval stamina and survival in both 0 and 60 mg L,1 salinity water by 13% and 22.9% respectively. These improvements in the larval quality at the early stages of fish development are important for the efficiency of intensive hatchery production. [source] Growth, salinity tolerance and microsatellite analysis of the F2 reciprocal hybrids of Oreochromis niloticus×Sarotherodon galilaeus at different salinitiesAQUACULTURE RESEARCH, Issue 9 2010Biao Yan Abstract Oreochromisniloticus (O), the sixth generation of Genetic Improvement of Farmed Tilapia, shows rapid growth but poor salt tolerance, while Sarotherodon galilaeus (S) exhibits opposite traits. To combine the traits, F1 progeny was obtained through artificial fertilization. Fertile F1 produced F2 by natural spawning. The mean survival times, the median survival time (ST50) or the survival rate of hybrids was greater than O. niloticus in a gradual or an acute salinity change. Plasma osmolarity, [Na+] and [Cl,] of the hybrids fluctuated in 32 g L,1 water during a 24-h period, but eventually reached levels similar to fish in freshwater. O. niloticus,×S. galilaeus, (OS F2) or S. galilaeus,×O. niloticus, (SO F2) showed the fastest growth at 22.5 g L,1, equal to about 78.2% or 69.7% of O. niloticus at 0 and 3.87 or 3.45 times that of S. galilaeus at their individual optimum growth. Growth in OS F2 was 12% faster than SO F2. Microsatellite analysis showed that F2 had more alleles, a higher polymorphism information content and greater observed and expected heterozygosity than O. or S. Population differentiation was not detected between F1 and F2. All the results indicated that F2 could be exploited for commercial production under saline conditions. [source] Effect of salinity on survival, growth, oxygen consumption and ammonia-N excretion of juvenile whiteleg shrimp, Litopenaeus vannameiAQUACULTURE RESEARCH, Issue 12 2009Peidong Zhang Abstract In this study, we tested the lower salinity tolerance of juvenile shrimps (Litopenaeus vannamei) at a relatively low temperature (20 °C). In the first of two laboratory experiments, we first abruptly transferred shrimps (6.91 ± 0.05 g wet weight, mean ± SE) from the rearing salinity (35 000 mg L,1) to salinities of 5000, 15 000, 25 000, 35 000 (control) and 40 000 mg L,1 at 20 °C. The survival of L. vannamei juvenile was not affected by salinities from 15 000 to 40 000 mg L,1 during the 96-h exposure periods. Shrimps exposed to 5000 mg L,1 were significantly affected by salinity, with a survival of 12.5% after 96 h. The 24-, 48- and 96-h lethal salinity for 50% (LS50) were 7020, 8510 and 9540 mg L,1 respectively. In the second experiment, shrimps (5.47 ± 0.09 g wet weight, mean ± SE) were acclimatized to the different salinity levels (5000, 15 000, 25 000, 35 000 and 40 000 mg L,1) and then maintained for 30 days at 20 °C. Results showed that the survival was significantly lower at 5000 mg L,1 than at other salinity levels, but the final wet weight under 5000 mg L,1 treatment was significantly higher than those under other treatments (P<0.05). Feed intake (FI) of shrimp under 5000 mg L,1 was significantly lower than those of shrimp under 150 00,40 000 mg L,1; food conversion efficiency (FCE), however, showed a contrasting change (P<0.05). Furthermore, salinity significantly influenced the oxygen consumption rates, ammonia-N excretion rates and the O/N ratio of test shrimps (P<0.05). The results obtained in our work provide evidence that L. vannamei juveniles have limited capacity to tolerate salinities <10 000 mg L,1 at a relatively low temperature (20 °C). Results also show that L. vannamei juvenile can recover from the abrupt salinity change between 15 000 and 40 000 mg L,1 within 24 h. [source] Developing the harpacticoid copepod Tisbe biminiensis culture: testing for salinity tolerance, ration levels, presence of sediment and density dependent analysesAQUACULTURE RESEARCH, Issue 15 2006Lķlia P Souza-Santos Abstract Copepods have a number of advantages for use as live food in cultures of fish and crustacean larvae. This study aimed to develop culture techniques of Tisbe biminiensis Volkmann-Rocco 1973 in volumes of 500 mL. The first experiment tested the effect of salinity on survival and fecundity. The other experiments studied the population growth comparing two levels of daily ration and the effect of sand sediment in cultures. The cultures were carried out on plastic boxes at 29°C, salinity of 34 g L,1 and 12 h light/12 h dark photoperiod with aerated filtered seawater, total renewal every other day. Adult females tolerated the decrease of salinity from 34 to 27 g L,1 but the offspring production decreased significantly. The salinity of 20 g L,1 was not tolerated at all. Tisbe biminiensis attained one of the highest rates of increase in cultures among harpacticoids (0.33 day,1) and a high density of 205 individual ind. mL,1. The carrying capacity of the population was estimated as 67 200 ind. in 500 mL recipients. In conclusion, T. biminiensis grow fast and attain high densities in cultures of 500 mL volume without sediment, feeding a daily ration of 50,100% of copepodite biomass. [source] DNA markers for estimation of inbreeding depression and heterosis in the guppy Poecilia reticulataAQUACULTURE RESEARCH, Issue 11 2003Takahito Shikano Abstract Molecular markers have significant potential for use in precise breeding programmes in aquaculture. This paper reviews the use of DNA markers to estimate inbreeding depression and heterosis in the guppy Poecilia reticulata. Full-sib matings revealed that inbreeding causes declines in survival and salinity tolerance, but not in undwarfism, growth and high water temperature tolerance, indicating the effects of inbreeding differ among fitness-related traits. Salinity tolerance was used to quantify the level of inbreeding depression and heterosis because the trait is strongly sensitive to inbreeding and shows a linear decrease with an increase in inbreeding coefficient. A positive correlation was observed between heterozygosity at microsatellite loci and salinity tolerance among 17 guppy populations. This indicates that heterozygosity estimated from microsatellites is a useful indicator for the estimation of inbreeding depression, suggesting that overall heterozygosity is important for fitness-related traits that show inbreeding depression. Use of DNA markers to estimate the amount of heterosis in various strain combinations was examined using diallele and reciprocal crosses among four domestic strains. The amount of heterosis differed among the strain combinations and correlated with Nei's genetic distance measured by microsatellites and also by dissimilarity using random amplified polymorphic DNA (RAPD) analysis. This indicates that microsatellite and RAPD markers are useful for estimating the amount of heterosis in various strain combinations, further suggesting that the amount of heterosis depends on the genetic differences between the strains. The present study showed that DNA markers are useful tools for estimating inbreeding depression and heterosis in guppy breeding. [source] Effects of Light Intensity and Salinity on Growth, Survival, and Whole-Body Osmolality of Larval Southern Flounder Paralichthys lethostigmaJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 4 2003James P. Henne The southern flounder Paralichthys lethosligma is a high-valued flatfish found in estuarine and shelf waters of the south Atlantic and Gulf coasts of the United States. Wide temperature and salinity tolerances exhibited by juveniles and adults make it a versatile new candidate for commercial culture, and studies are underway in the southeastern U.S. to develop hatchery methods for this species. The objectives of this study were to establish illumination and salinity conditions that optimize growth and survival of larval southern flounder reared through the yolk-sac and first feeding stages to 15-d post-hatching (15 dph). Early embryos were stocked into black 15-L tanks under light intensities of 5, 50, 100, and 1,000 Ix and at salinities of 24 and 34 ppt in a 4 ± 2 factorial design. Significant (P 0.05) effects of both light intensity and salinity on growth and survival were obtained, with no interaction between these effects. On 11 dph and 15 dph, growth was generally maximized at the intermediate light intensities (50 and 100 Ix) and minimized at the extremes (5 and 1,000 Ix). By 15 dph, growth was higher at 34 ppt than at 24 ppt. Survival to 15 dph showed trends similar to those of growth. Survival was higher at 100 Ix (avg. = 46%, range = 41,54%) than at 5 Ix (avg. = 11%, range = 6,17%) and higher at 34 ppt (avg. = 43%, range = 3145%) than at 24 ppt (avg. = 17%, range = 8,38%). Whole-body osmolality (mOsmol/kg) was significantly lower in larvae reared at 24 ppt (avg. = 304, range = 285,325) through 11 dph than in larvae reared at 34 ppt (avg. = 343, range = 296,405). Larvae reared under the extreme light intensity treatments (5 and 1,000 Ix) at 34 ppt appeared to exhibit osmoregulatory stress, particularly on 11 dph, when a marked increase in whole-body osmolality was observed. The mid-intensity treatments (50 and 100 Ix) at 34 ppt optimized growth and survival of larval southern flounder in this study; and elicited the most stable osmotic response. These conditions appear to be consistent with those that southern flounder larvae encounter in nature during this early developmental period. 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