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31.
Presenilins play prominent roles in the molecular pathogenesis of Alzheimer's disease and during embryo development. We have isolated a zebrafish presenilin orthologue (pre2), which shows a high degree of sequence identity to the human PS2 protein. Zebrafish pre2 is maternally and ubiquitously expressed during early embryo development, whereas Pre2 protein expression is initiated between 6 and 12 hours post fertilisation (hpf), suggesting strict regulation of pre2 translation. pre2 expression is especially high in neural-crest-derived melanocytes. 相似文献
32.
We determined the hearing sensitivity of the little skate, Raja erinacea using two methods: Behavioral conditioning and the auditory brainstem response (ABR). This marks the first time that the hearing in any member of the Rajiformes has been examined and the first time that the ABR method has been used with an elasmobranch. We obtained audiograms of R. erinacea using each method and were found to be statistically similar. The best hearing sensitivity for R. erinacea was between 100 and 300Hz. We compared the audiograms to audiograms obtained from other species of elasmobranchs. This analysis showed that R. erinacea, a bottom-dwelling elasmobranch, has less sensitive hearing than the lemon shark, Negaprion brevirostris, and the bull shark, Carcharhinus leucas, a free-swimming, raptorial elasmobranch. However, R. erinacea showed sensitivity comparable to that of the horn shark, Heterodontus francisi, another bottom-dwelling elasmobranch; both species feed primarily on benthic prey. These findings are in agreement with Corwin's hypothesis (1978) that hearing sensitivity is correlated with feeding behavior. An examination of the macula neglecta of R. erinacea found a total count of 10000 hair cells, which is within the range of other bottom-dwelling elasmobranchs. 相似文献
33.
Johnson SP Jang S Gulland FM Miller MA Casper DR Lawrence J Herrera J 《Journal of wildlife diseases》2003,39(1):136-144
Between 1994 and 2000, 141 Arcanobacterium phocae isolates were recovered from marine mammals that stranded along the central California coast (USA). Arcanobacterium phocae was cultured from tissue sites with abnormal discharge or evidence of inflammation in 66 California sea lions (Zalophus californianus), 50 Pacific harbor seals (Phoca vitulina richardii), 19 northern elephant seals (Mirounga angustirostris), five southern sea otters (Enhydra lutris nereis), and one common dolphin (Delphinus delphis). The overall prevalence of A. phocae among cultured stranded marine mammals was 8%. This is the first report of A. phocae in animals from the Pacific Ocean. Sequence analysis of a portion of the 16S ribosomal RNA gene confirmed recent isolates as A. phocae. Prior to phylogenetic testing and the routine use of the esculin hydrolysis and motility tests, A. phocae isolates may have been misidentified as Listeria ivanovii. Arcanobacterium phocae was commonly isolated from superficial abscesses, was often present in mixed infections, and was susceptible to all antimicrobial agents tested. 相似文献
34.
High-rate evolution of Saccharomyces sensu lato chromosomes 总被引:1,自引:0,他引:1
Spírek M Yang J Groth C Petersen RF Langkjaer RB Naumova ES Sulo P Naumov GI Piskur J 《FEMS yeast research》2003,3(4):363-373
35.
Heat shock in the developmentally sensitive period of butterfly eyespots fails to increase fluctuating asymmetry 总被引:1,自引:0,他引:1
Fluctuating asymmetry (FA) is considered to provide a means of evaluating developmental stability and to reflect an individual's quality or the stress experienced during development. Stress is predicted to increase the phenotypic variation of both FA and trait size. In this study we examined the effect of a particular heat shock on both FA and size of eyespots in the butterfly, Bicyclus anynana. We also examined whether those eyespots thought to be involved in partner choice and sexual selection were particularly sensitive to stress. We applied a heat shock of 39.5 degrees C for 3 h before, during, and after a sensitive period in eyespot development. We examined the FA, variation in FA, size, and variation in size of five eyespots, two on the dorsal forewing (sexually selected traits), two on the ventral forewing, and one on the ventral hindwing (nonsexually selected traits). For each sex and treatment, the heat shock did not result in significant changes in mean trait size and FA nor in the variation of size and FA. There were no differences in the response to the heat shock between sexually and nonsexually selected traits. We discuss how the increased production of heat shock proteins, including HSP60, may have stabilized development and how this might explain the results. 相似文献
36.
Hoogenraad CC Wulf P Schiefermeier N Stepanova T Galjart N Small JV Grosveld F de Zeeuw CI Akhmanova A 《The EMBO journal》2003,22(22):6004-6015
Bicaudal D is an evolutionarily conserved protein, which is involved in dynein-mediated motility both in Drosophila and in mammals. Here we report that the N-terminal portion of human Bicaudal D2 (BICD2) is capable of inducing microtubule minus end-directed movement independently of the molecular context. This characteristic offers a new tool to exploit the relocalization of different cellular components by using appropriate targeting motifs. Here, we use the BICD2 N-terminal domain as a chimera with mitochondria and peroxisome-anchoring sequences to demonstrate the rapid dynein-mediated transport of selected organelles. Surprisingly, unlike other cytoplasmic dynein-mediated processes, this transport shows very low sensitivity to overexpression of the dynactin subunit dynamitin. The dynein-recruiting activity of the BICD2 N-terminal domain is reduced within the full-length molecule, indicating that the C-terminal part of the protein might regulate the interaction between BICD2 and the motor complex. Our findings provide a novel model system for dissection of the molecular mechanism of dynein motility. 相似文献
37.
1. In situ exclosure experiments in the Mississippi and Ohio Rivers determined the importance of fish predation in regulating zebra mussels (Dreissena polymorpha), an increasingly important constituent of the benthic invertebrate assemblages in both rivers. 2. We evaluated the effects of predatory fish on the density, biomass and size distribution of zebra mussels in a floodplain reach of the upper Mississippi River and in a naturally constrained reach of the Ohio River. Fifty, six-sided, predator-exclusion cages and fifty ‘partial’ cages (mesh at the upstream end only) were deployed, with half the cages containing willow snags and half clay tiles suspended 12–16 cm above the bottom. A single snag or tile sample unit was removed from each cage at approximately monthly intervals from July to October 1994. Types and relative abundances of molluscivorous fish were evaluated by electrofishing near the cages in both rivers. Actual and potential recruitment of young zebra mussels on to the substrata were measured using benthic samples in both rivers and estimated (Ohio River only) from counts of planktonic veligers. 3. Zebra mussels were consumed by at least three fish species in the upper Mississippi River (mostly carp, Cyprinus carpio, and redhorse suckers, Moxostoma sp.) and five species in the Ohio River (primarily smallmouth buffalo, Ictiobus bubalus, and channel catfish, Ictalurus punctatus), but potential recruitment seemed adequate to replace consumed mussels, at least in the Ohio River. The number of juvenile benthic mussels showed no apparent link with the density of veligers soon after initiation of reproduction. Recruitment of juveniles on snags and tiles was not affected by cage type (thus eliminating a potentially confounding ‘cage effect’). 4. Fish significantly influenced mussel populations, but the impact was often greatest among low density populations in the upper Mississippi. Density and biomass differed in both rivers for cage type (higher inside cages), substratum (greater on tiles), and date (increased over time). Presumed size-selective predation was present in the Mississippi (greater on larger size classes) but was not evident in the Ohio. We hypothesize that fish in the Mississippi can more easily select larger prey from the low density populations; whereas size-selective predation on tightly packed zebra mussels in the Ohio would be difficult. 5. Although fish can reduce numbers of Dreissena polymorpha in the two rivers, current levels of fish predation seem insufficient to regulate zebra mussel densities because of its great reproductive capacity. The recent invasion of zebra mussels, however, could lead to larger fish populations while promoting greater carbon retention and overall ecosystem secondary production. 相似文献
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Clara?D. van?Karnebeek William?S. Sly Colin?J. Ross Ramona Salvarinova Joy Yaplito-Lee Saikat Santra Casper Shyr Gabriella?A. Horvath Patrice Eydoux Anna?M. Lehman Virginie Bernard Theresa Newlove Henry Ukpeh Anupam Chakrapani Mary?Anne Preece Sarah Ball James Pitt Hilary?D. Vallance Marion Coulter-Mackie Hien Nguyen Lin-Hua Zhang Amit?P. Bhavsar Graham Sinclair Abdul Waheed Wyeth?W. Wasserman Sylvia Stockler-Ipsiroglu 《American journal of human genetics》2014,94(3):453-461
Four children in three unrelated families (one consanguineous) presented with lethargy, hyperlactatemia, and hyperammonemia of unexplained origin during the neonatal period and early childhood. We identified and validated three different CA5A alterations, including a homozygous missense mutation (c.697T>C) in two siblings, a homozygous splice site mutation (c.555G>A) leading to skipping of exon 4, and a homozygous 4 kb deletion of exon 6. The deleterious nature of the homozygous mutation c.697T>C (p.Ser233Pro) was demonstrated by reduced enzymatic activity and increased temperature sensitivity. Carbonic anhydrase VA (CA-VA) was absent in liver in the child with the homozygous exon 6 deletion. The metabolite profiles in the affected individuals fit CA-VA deficiency, showing evidence of impaired provision of bicarbonate to the four enzymes that participate in key pathways in intermediary metabolism: carbamoylphosphate synthetase 1 (urea cycle), pyruvate carboxylase (anaplerosis, gluconeogenesis), propionyl-CoA carboxylase, and 3-methylcrotonyl-CoA carboxylase (branched chain amino acids catabolism). In the three children who were administered carglumic acid, hyperammonemia resolved. CA-VA deficiency should therefore be added to urea cycle defects, organic acidurias, and pyruvate carboxylase deficiency as a treatable condition in the differential diagnosis of hyperammonemia in the neonate and young child. 相似文献