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Live Observation (live + observation)
Selected AbstractsPax6 transcription factor is required for the interkinetic nuclear movement of neuroepithelial cellsGENES TO CELLS, Issue 9 2007Hiroshi Tamai The mammalian cerebral cortex develops from proliferative neuroepithelial cells that exhibit a cell cycle-dependent nuclear movement (interkinetic nuclear migration; INM). Pax6 transcription factor plays pivotal roles in various aspects of corticogenesis. From live observation using cultured cortical slices from the Pax6 mutant rat, we identified the premature descent of S phase cells, the unsteady ascent or descent of G2 phase cells, and ectopic cell division within the basal side of the ventricular zone (VZ). The centrosome normally stayed at the most apical side, apart from the nucleus, in the neuroepithelial cell during the S to G2 phase, while the Pax6 mutant showed unstable movement of the centrosome associated with an abnormal INM. Our results suggest the possibility that Pax6 regulates the INM by stabilizing the centrosome at the apical side. [source] Descriptions of Protospathidium serpens (Kahl, 1930) and P. fraterculum n. sp. (Ciliophora, Haptoria), Two Species Based on Different Resting Cyst MorphologyTHE JOURNAL OF EUKARYOTIC MICROBIOLOGY, Issue 4 2005KUIDONG XU Abstract. Protospathidium serpens (Kahl, 1930) is frequent in semiterrestrial and terrestrial habitats worldwide. Conventionally, all populations are considered as conspecific because they have very similar overall morphologies and morphometrics. We studied in detail not only the morphology of the vegetative cells but also the resting cysts using live observation, protargol impregnation, and scanning electron microscopy. These revealed a cryptic diversity and biogeographic pattern in details of the dorsal brush and cyst wall morphology. The cyst wall is spiny in the Austrian specimens, while smooth in the South African and Antarctic populations. Accordingly, P. serpens consists of at least two species: P. serpens (with spiny cyst wall) and P. fraterculum n. sp. (with smooth cyst wall); the latter is probably composed of two distinct taxa differing by the absence (South African)/presence (Antarctic) of a monokinetidal bristle tail in brush row 3, the number of dikinetids comprising brush row 1 (seven versus three), and the total number of brush dikinetids (29 versus 17). Protospathidium serpens is neotypified with the new population from Austria. The significance of resting cyst morphology is discussed with respect to alpha-taxonomy and overall ciliate diversity. [source] Morphology and Infraciliature of Three Species of Metaurostylopsis (Ciliophora, Stichotrichia): M. songi n. sp., M. salina n. sp., and M. marina (Kahl 1932) from Sediments, Saline Ponds, and Coastal WatersTHE JOURNAL OF EUKARYOTIC MICROBIOLOGY, Issue 1 2005Yanli Lei Abstract. Two new urostylid ciliates, Metaurostylopsis songi n. sp. and Metaurostylopsis salina n. sp. and Metaurostylopsis marina (Kahl 1932) are investigated using live observation and protargol impregnation. These species were isolated in Korea from intertidal sediments, saline ponds, and coastal waters. Metaurostylopsis songi is in vivo about 120 ,m × 25 ,m, has a slenderly ellipsoidal body, colorless cortical granules in rows on ventral and dorsal body sides, about 54 macronuclear nodules, 28,47 adoral membranelles, five frontal, two or three frontoterminal and six or seven transverse cirri, and 9,12 midventral cirral pairs followed posteriorly by 1,3 single cirri. In vivo M. salina is about 60 ,m × 25 ,m, has a pyriform body, colorless cortical granules irregularly arranged, about 45 macronuclear nodules, 18,23 adoral membranelles, three frontal, three to five frontoterminal and two to five transverse cirri, and four or five midventral cirral pairs followed posteriorly by five to seven single cirri. Both species have three marginal cirral rows on each body side and 3 long dorsal kineties. The Korean specimens of M. marina match the Chinese population in all main features. Metaurostylopsis songi differs from M. marina by the more slender body, the number of frontal cirri (invariably five vs. four), and the arrangement of cortical granules (in rows on dorsal and ventral cortex vs. only along dorsal kineties and anterior body margin). Metaurostylopsis salina differs from its congeners by the distinctly smaller size, the pyriform body shape, the scattered cortical granules (vs. in rows), and number of frontal cirri. It differs from M. marina also by the number of midventral cirral pairs (four or five vs. seven to 11). [source] Morphological, Small Subunit rRNA, and Physiological Characterization of Trimyema minutum (Kahl, 1931), an Anaerobic Ciliate from Submarine Hydrothermal Vents Growing from 28°C to 52°CTHE JOURNAL OF EUKARYOTIC MICROBIOLOGY, Issue 3 2002MANUELA BAUMGARTNER ABSTRACT. A thermophilic strain of Trimyema minutum was isolated from the hydrothermally heated sea floor at Vulcano Island (Italy) and cultivated monoxenically on Marinobaaer sp. and Methanococcus thermolithotrophicus. It can be propagated strictly an aerobically and is sensitive to oxygen: if exposed to air at 48°C all cells die within 60 min. It grows from 0.45,7.2% (w/v) salt and at pH 6.0,8.0. The isolate is the most extreme thermophilic ciliate which ever has been cultivated, exhibiting an optimal growth temperature of 48°C (doubling time 6 h). Growth occurs between 28°C and 52°C. Trimyema minutum is redescribed using live observation and silver impregnation. Its morphology and the small subunit ribosomal RNA sequence is distinctly different from that of T. compressum, but morphology is highly similar to that of T. shoalsiaNerad et al. 1995, which is thus probably a junior synonym of T. minutum. To stabilize the bewildering species taxonomy in Trimyema. we suggest to recognize our population as a neotype of T. minutum. [source] Within- and between-year variation in the juvenile survival of Common Guillemots Uria aalgeIBIS, Issue 3 2007MICHAEL P. HARRIS We studied juvenile survival of 20 cohorts of Common Guillemot Uria aalge chicks colour-ringed on the Isle of May, Scotland, using both live observations at the colony and dead recoveries, allowing estimation of fidelity to the colony as well as survival. In this seabird, chicks leave the colony when only partly grown and are cared for by the male parent for several weeks afterwards. First-year survival varied strongly between cohorts, with a mean of 56% (range 30,91%). We did not identify any covariates which could explain this variation, whether relating to climate, population size or prey density. Survival was low during two regime shift episodes in the North Sea (1987,90 and 2000 onwards). Early hatched chicks were substantially more likely to survive than those hatching later in most years, whereas body condition at ringing had no detectable effect. Ringing recoveries indicated that mortality was highest in mid-winter, i.e. well after the cessation of paternal care. These results do not support the hypothesis that variation in prey quantity or energy content before fledging is a primary driver of variation in juvenile survival. Rather, it seems that chicks of high-quality parents are more likely to survive, as high-quality females tend to lay earlier in the season, and high-quality males presumably are better able to prepare their chicks to survive their first winter at sea. Very few (4%) Guillemots emigrated permanently before age 3 years, but from age 5 onwards 25,30% of birds annually left the colony or otherwise became unobservable. [source] Anatomy and lifestyles of Early Cambrian priapulid worms exemplified by Corynetis and Anningvermis from the Maotianshan Shale (SW China)LETHAIA, Issue 1 2004DI-YING HUANG Accurate information on the anatomy and ecology of worms from the Cambrian Lagerstätten of SW China is sparse. The present study of two priapulid worms Anningvermis n. gen. and Corynetis Luo & Hu, 1999 from the Lower Cambrian Maotianshan Shale biota brings new information concerning the anatomical complexity, functional morphology and lifestyles of the Early Cambrian priapulids. Comparisons are made with Recent priapulids from Sweden (live observations, SEM). The cuspidate pharyngeal teeth of Anningvermis (circumoral pentagons) and the most peculiar radiating oral crown of Corynetis added to the very elongate pharynx of these two forms are interpreted as two different types of grasping apparatus possibly involved in the capture of small prey. Corynetis and Anningvermis are two representative examples of the Early Cambrian endobenthic communities largely dominated by priapulid worms (more than ten species in the Maotianshan Shale biota) and to a much lesser extent by brachiopods. Corynetis and Anningvermis were probably active mud-burrowers and predators of small meiobenthic animals. Likewise predator priapulid worms exploited the interface layer between the seawater and bottom sediment, where meiobenthic organisms were abundant and functioned as prey. This implies that complex prey-predator relationship between communities already existed in the Early Cambrian. This study also shows that the circumoral pentagonal teeth and caudal appendage were present in the early stages of the evolutionary history of the group and were important features of the priapulid body plan already in the Early Cambrian. Two new families, one new genus and new species are introduced and described in the appendix. [source] Two New Species of Symbiotic Ciliates from the Respiratory Tract of Cetaceans with Establishment of the New Genus Planilamina n. gen. (Dysteriida, Kyaroikeidae)THE JOURNAL OF EUKARYOTIC MICROBIOLOGY, Issue 6 2006HONGWEI MA ABSTRACT. Examination of mucus discharged from the blowhole of Atlantic bottlenose dolphin (Tursiops truncatus) at Marine Life Oceanarium, Gulfport, Mississippi, and false killer whale (Pseudorca crassidens) and Atlantic bottlenose dolphin at SeaWorld Orlando, Orlando, Florida, using live observations and protargol impregnation revealed mixed infections of Kyaroikeus cetarius and two new species. Planilamina n. gen. is characterized by a C-shaped argentophilic band located along the laterally flattened margin of cell and extending from the cell apex to subposterior cone-shaped podite; a deep oral cavity containing one short preoral kinety, two circumoral kineties, seven to 13 infundibular kineties, and a cytostome; a broadly funnel-shaped cytopharynx reinforced by argentophilic fibers but without nematodesmata; closely packed postoral kinetofragments set in a pocket located anterior left of the podite; and somatic kineties as a right field closely situated at the right surface and a left field bordering the anterior left margin of the oral cavity. The type species for the genus, Planilamina ovata n. sp., is distinguished from its sister species Planilamina magna n. sp. by the following characteristics: body size (28,65 × 20,43 ,m vs. 57,90 × 40,63 ,m), number of right field kineties (38,55 vs. 79,99), and position of the anterior end of the leftmost kinety in the right somatic field (anterior one-third vs. mid-body). The morphogenesis of Planilamina ovata is similar to that of K. cetarius. The diagnosis of Kyaroikeidae is emended to accommodate the new genus. [source] | ||||||||||