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151.
Homero P. Vallada John E. Collins Ian Dunham Elisabeth Dawson Robin M. Murray Michael Gill David A. Collier 《Human genetics》1994,93(6):688-690
We have constructed a linkage map of 14 short tandem repeat polymorphisms (11 with heterozygosity > 70%) on the long arm of human chromosome 22 using 23 non-CEPH pedigrees. Twelve of the markers could be positioned uniquely with a likelihood of at least 1,000:1, and distributed at an average distance of 6.62 cM (range 1.5–16.1 cM). The sex-combined map covers a total of 79.6 cM, the female map 93.2 cM and the male map 64.6 cM. Based on comparisons between physical maps and other genetic maps, we estimate that our map covers 70%–80% of the chromosome. The map integrates markers from previous genetic maps and uniquely positions one marker (D22S307). Data from physical mapping on the location of four genetic markers correlates well with our linkage map, and provides information on an additional marker (D22S315). This map will facilitate high resolution mapping of additional polymorphic loci and disease genes on chromosome 22, and act as a reference for building and verifying physical maps. 相似文献
152.
The expression of smooth muscle myosin light chain kinase (MLCK) was investigated during chicken gizzard development. The molecular weight and the antigenic properties of MLCK did not change during development. The use of anion exchange high performance liquid chromatography (HPLC) enabled us to distinguish between MLCKs from post-hatched and adult chickens. A partial amino acid sequence determination of 4-day-old gizzard MLCK failed to disclose differences in the primary sequences of the two proteins. The results suggest that MLCK has the same primary sequence in all sequences of the two proteins. The results suggest that MLCK has the same primary sequence in all stages of gizzard development, although charge variants due to post-translational modifications may exist. 相似文献
153.
N. Rehman A. R. Collins T. K. Suh R. W. Wright 《Molecular reproduction and development》1994,38(3):251-255
Development of 8-cell bovine embryos derived from in vitro matured/in vitro fertilized (IVM/IVF) oocytes was evaluated in two simple, serum-free media (CZB and SOM) with buffalo rat liver cells co-culture (BRLC) or after conditioning compared to a commonly used, serum-supplemented complex medium TCM-199. In a 3 x 4 factorial design, 578 eight-cell embryos were randomly assigned to 12 treatment groups. The factors were: first, type of culture medium (M199/FBS, CZBg and SOM), and second, the use of BRLC (as co-culture or to condition media for 24 hr and 48 hr) and unconditioned media. Development to morula was not affected by the type of medium, but co-culture and 48 hr conditioning within media type resulted in better development when compared to the 24-hr conditioned or unconditioned groups. Blastocyst development in SOM (38.9%) was different (P < 0.05) than in CZBg (46.6%) and M199/FBS (48.7%) and was lowest in the unconditioned group (27.8%) followed by 24 hr conditioned (33.3%), 48 hr (56.3%), and co-culture (59.6%). No blastocyst expansion was observed with unconditioned media and 24 hr conditioned SOM. Significant differences (P < 0.05) were found among all treatment groups except the co-culture and 48-hr conditioned groups. Hatching occurred only with co-culture and 48-hr conditioned groups of M199/FBS and CZBg media. These data show that CZB with glucose conditioned by BRLC monolayers for 48 hr can support the development of IVM/IVF produced bovine embryos to blastocyst compared to culture in TCM-199 with serum. © 1994 Wiley-Liss, Inc. 相似文献
154.
Kin recognition and cannibalism in polyphenic salamanders 总被引:3,自引:1,他引:2
We investigated kin discrimination among larvae of Arizona tigersalamanders (Ambystoma tigrinum nebulosum) which occur as "typical"morphs that feed mostly on invertebrate prey and occasionallyon conspecifics, and as "cannibal" morphs that feed primarilyon conspecifics. When housed with smaller larvae that differedin relatedness, both cannibals and typicals preferentially consumedless-related individuals. Cannibals ate typicals much quickerwhen the choice was between nonkin and siblings than when thechoice was between nonkin and cousins, indicating that cannibalscould distinguish different categories of relatives. Cannibalswere less likely to eat a larval sibling that was a cannibalmorph than a sibling that was a typical morph. Occluding animals'nares temporarily eliminated kin discrimination, implying thatolfaction is important in recognition. Larvae from differentsibships varied considerably in their ability to discriminatekin, and the greater the probability that a larva from a givensibship would develop into a cannibal morph, the more likelythe members of that sibship were to discriminate kin. Our resultsenable us to infer the functional significance of kin recognitionin this species and to develop an evolutionary model of themechanisms underlying the joint control of kin recognition andcannibalistic polyphenism. 相似文献
155.
Gregory M. L. Patterson Kathleen K. Baker Cynthia L. Baldwin Christine M. Bolis Faith R. Caplan Linda K. Larsen Ira A. Levine Richard E. Moore E. Moore Carrie S. Nelson Kathryn D. Tschappat Grace D. Tuang Michael R. Boyd John H. Cardellina Ralph P. Collins Kirk R. Gustafson Kenneth M. Snader Owen S. Weislow Ralph A. Lewin 《Journal of phycology》1993,29(1):125-130
Lipophilic and hydrophilic extracts from approximately 600 strains of cultured cyanophytes, representing some 300 species, were examined for antiviral activity against three pathogenic viruses. Approximately 10% of the cultures produced substances that caused significant reduction in cytopathic effect normally associated with viral infection. The screening program identified the order Chroococcales as commonly producing antiviral agents. 相似文献
156.
Jeffrey S. Chamberlain Michael Boehnke Thomas S. Frank Sam Kiousis Junxhe Xu Sun-Wei Guo Elizabeth R. Hauser Robert A. Norum Elizabeth A. Helmbold Dorene S. Markel Sima M. Keshavarzi C. Eugene Jackson Kathleen Calzone Judy Garber Francis S. Collins Barbara L. Weber 《American journal of human genetics》1993,52(4):792-798
Previous studies have demonstrated linkage between early-onset breast cancer and ovarian cancer and genetic markers on chromosome 17q21. These markers define the location of a gene (BRCA1) which appears to be inherited as an autosomal dominant susceptibility allele. We analyzed five families with multiple affected individuals for evidence of linkage to the BRCA1 region. Two of the five families appear to be linked to BRCA1. One apparently linked family contains critical recombinants, suggesting that the gene is proximal to the marker D17S579 (Mfd188). These findings are consistent with the maximum-likelihood position estimated by the Breast Cancer Linkage Consortium and with recombination events detected in other linked families. Linkage analysis was greatly aided by PCR-based analysis of paraffin-embedded normal breast tissue from deceased family members, demonstrating the feasibility and importance of this approach. One of the two families with evidence of linkage between breast cancer and genetic markers flanking BRCA1 represents the first such family of African-American descent to be reported in detail. 相似文献
157.
The tiger salamander,Ambystoma tigrinum, is a geographically widespread, morphologically variable, polytipic species. It is among the most variable species of salamanders
in morphology and life history with two larval morphs (typical and cannibal) and three adult morphs (metamorphosed, typical
branchiate, cannibal branchiate) that vary in frequency between subspecies and between populations within subspecies. We report
morphometric evidence suggesting that branchiate cannibals arose through intraspecific change in the onset or timing of development
resulting in the wider head and hypertrophied tooth-bearing skull bones characteristic of this phenotype. We also quantified
bilateral symmetry of gill raker counts and abnormalities, then evaluated fluctuating asymmetry as a measure of the developmental
stability of each morph. There was a significant interaction between fluctuating asymmetry of developmental abnormalities
in cannibals and typicals and the locality where they were collected, suggesting that relative stability of each phenotype
could vary among populations. While altered timing of developmental events appears to have a role in the evolution and maintenance
of morphs, novel phenotypes persist only under favorable ecological conditions. Predictability of the aquatic habitat, genetic
variation, kinship, body size, intraspecific competition and predation all affect expression and survival of the morphs inA. tigrinum. This taxon provides an excellent model for understanding the diversity and complexity of developmental and ecological variables
controlling the evolution and maintenance of novel phenotypes. 相似文献
158.
Differential regulation of vascular cell adhesion molecule 1 gene expression by specific NF-kappa B subunits in endothelial and epithelial cells. 总被引:21,自引:5,他引:16 下载免费PDF全文
H B Shu A B Agranoff E G Nabel K Leung C S Duckett A S Neish T Collins G J Nabel 《Molecular and cellular biology》1993,13(10):6283-6289
159.
As above,not so below: Long-term dynamics of net primary production across a dryland transition zone
Drylands are key contributors to interannual variation in the terrestrial carbon sink, which has been attributed primarily to broad-scale climatic anomalies that disproportionately affect net primary production (NPP) in these ecosystems. Current knowledge around the patterns and controls of NPP is based largely on measurements of aboveground net primary production (ANPP), particularly in the context of altered precipitation regimes. Limited evidence suggests belowground net primary production (BNPP), a major input to the terrestrial carbon pool, may respond differently than ANPP to precipitation, as well as other drivers of environmental change, such as nitrogen deposition and fire. Yet long-term measurements of BNPP are rare, contributing to uncertainty in carbon cycle assessments. Here, we used 16 years of annual NPP measurements to investigate responses of ANPP and BNPP to several environmental change drivers across a grassland–shrubland transition zone in the northern Chihuahuan Desert. ANPP was positively correlated with annual precipitation across this landscape; however, this relationship was weaker within sites. BNPP, on the other hand, was weakly correlated with precipitation only in Chihuahuan Desert shrubland. Although NPP generally exhibited similar trends among sites, temporal correlations between ANPP and BNPP within sites were weak. We found chronic nitrogen enrichment stimulated ANPP, whereas a one-time prescribed burn reduced ANPP for nearly a decade. Surprisingly, BNPP was largely unaffected by these factors. Together, our results suggest that BNPP is driven by a different set of controls than ANPP. Furthermore, our findings imply belowground production cannot be inferred from aboveground measurements in dryland ecosystems. Improving understanding around the patterns and controls of dryland NPP at interannual to decadal scales is fundamentally important because of their measurable impact on the global carbon cycle. This study underscores the need for more long-term measurements of BNPP to improve assessments of the terrestrial carbon sink, particularly in the context of ongoing environmental change. 相似文献
160.
Use of the polymerase chain reaction and 16S rRNA sequences for the rapid detection of Brochothrix spp. in foods 总被引:5,自引:2,他引:3
K.A. Grant J.H. Dickinson M.J. Payne Shona Campbell M.D. Collins R.G. Kroll 《Journal of applied microbiology》1993,74(3):260-267
Oligonucleotide primers were designed against rRNA sequences to give a DNA-based PCR assay for the rapid identification/detection of Brochothrix spp. The PCR products could be confirmed by hybridization to an internal oligonucleotide probe. The method successfully and sensitively detected/identified these organisms in pure cultures but was of limited value as a detection method because the detection sensitivity, in relation to conventional plate counts, varied and the assay sensitivity was reduced in the presence of staphylococci. Furthermore, sensitivity was also lost when the assay was applied directly to meat samples. However, a separation step using a lectin (from Agaricus bisporus ) immobilized on magnetic beads prior to the PCR assay, allowed the direct detection of low numbers (> 10 cfu g-1 ) of Brochothrix in meat samples within a working day. 相似文献