排序方式: 共有30条查询结果,搜索用时 265 毫秒
1.
Bone morphometrics and tetracycline marking patterns in young growing American alligators (Alligator mississippiensis) 总被引:1,自引:0,他引:1
Nine young American alligators (Alligator mississippiensis) were injected at monthly intervals with tetracycline to determine the bone apposition rate and the resorption patterns over a 3-mo period. The periosteal apposition rate increased progressively over the 3-mo period from 2.99 microns/day to 5.94 microns/day. Endosteal apposition rate was much slower with incomplete tetracycline lines being observed on the endosteum. This suggests that most modeling-resorptive activities occur on the endosteal envelope. 相似文献
2.
J. R. Gold T. L. King † L. R. Richardson D. A. Bohlmeyer G. C. Matlock † 《Journal of fish biology》1994,44(4):567-590
Nine polymorphic nuclear-gene (allozyme) loci were surveyed among 491 red drum ( Sciaenops ocellatus ) sampled in 1988 and 1989 from nearshore localities in the northern Gulf of Mexico (Gulf) and the Atlantic coast of the southeastern United States (Atlantic). Data were combined with those from a previous study to generate a data set of 762 individuals representing 11 sample localities in the Gulf and 175 individuals representing five sample localities in the Atlantic. The combined data set included individuals from the 1986 and 1987 year classes and permitted rigorous testing of both temporal and spatial genetic heterogeneity. Average heterozygosity-per-locus values (estimated using 33 assumed monomorphic loci) were 0·048 (Gulf red drum) and 0·046 (Atlantic red drum). Tests of heterogeneity in allele frequencies between year classes at individual localities and across regions (Gulf and Atlantic) were non-significant. Tests of spatial (geographic) heterogeneity indicated that red drum are weakly subdivided: genetically-differentiated subpopulations occur in the northern Gulf and along the south-eastern Atlantic coast. Genetic data were consistent with the hypothesis that red drum within the Gulf and along the Atlantic coast comprise singie subpopulalions. Genetic differences between Gulf and Atlantic red drum seem likeiy to stem from historical or recent interactions between dispersal and impediments to gene flow. 相似文献
3.
4.
A human T-cell lymphotropic virus type 1 enhancer of Myc transforming potential stabilizes Myc-TIP60 transcriptional interactions 下载免费PDF全文
5.
Background
Nutrient management in rivers and streams is difficult due to the spatial and temporal variability of algal growth responses. The objectives of this project were to determine the spatial and seasonal in situ variability of trophic status in the Lake Waco/Bosque River watershed, determine the variability in the lotic ecosystem trophic status index (LETSI) at each site as indicators of the system's nutrient sensitivity, and determine if passive diffusion periphytometers could provide threshold algal responses to nutrient enrichment.Methods
We used the passive diffusion periphytometer to measure in-situ nutrient limitation and trophic status at eight sites in five streams in the Lake Waco/Bosque River Watershed in north-central Texas from July 1997 through October 1998. The chlorophyll a production in the periphytometers was used as an indicator of baseline chlorophyll a productivity and of maximum primary productivity (MPP) in response to nutrient enrichment (nitrogen and phosphorus). We evaluated the lotic ecosystem trophic status index (LETSI) using the ratio of baseline primary productivity to MPP, and evaluated the trophic class of each site.Results
The rivers and streams in the Lake Waco/Bosque River Watershed exhibited varying degrees of nutrient enrichment over the 18-month sampling period. The North Bosque River at the headwaters (NB-02) located below the Stephenville, Texas wastewater treatment outfall consistently exhibited the highest degree of water quality impact due to nutrient enrichment. Sites at the outlet of the watershed (NB-04 and NB-05) were the next most enriched sites. Trophic class varied for enriched sites over seasons.Conclusion
Seasonality played a significant role in the trophic class and sensitivity of each site to nutrients. Managing rivers and streams for nutrients will require methods for measuring in situ responses and sensitivities to nutrient enrichment. Nutrient enrichment periphytometers show significant potential for use in nutrient gradient studies. 相似文献6.
7.
8.
William Matlock Kevin K. Chau Manal AbuOun Emma Stubberfield Leanne Barker James Kavanagh Hayleah Pickford Daniel Gilson Richard P. Smith H. Soon Gweon Sarah J. Hoosdally Jeremy Swann Robert Sebra Mark J. Bailey Timothy E. A. Peto Derrick W. Crook Muna F. Anjum Daniel S. Read A. Sarah Walker Nicole Stoesser Liam P. Shaw REHAB consortium 《The ISME journal》2021,15(8):2322
F-type plasmids are diverse and of great clinical significance, often carrying genes conferring antimicrobial resistance (AMR) such as extended-spectrum β-lactamases, particularly in Enterobacterales. Organising this plasmid diversity is challenging, and current knowledge is largely based on plasmids from clinical settings. Here, we present a network community analysis of a large survey of F-type plasmids from environmental (influent, effluent and upstream/downstream waterways surrounding wastewater treatment works) and livestock settings. We use a tractable and scalable methodology to examine the relationship between plasmid metadata and network communities. This reveals how niche (sampling compartment and host genera) partition and shape plasmid diversity. We also perform pangenome-style analyses on network communities. We show that such communities define unique combinations of core genes, with limited overlap. Building plasmid phylogenies based on alignments of these core genes, we demonstrate that plasmid accessory function is closely linked to core gene content. Taken together, our results suggest that stable F-type plasmid backbone structures can persist in environmental settings while allowing dramatic variation in accessory gene content that may be linked to niche adaptation. The association of F-type plasmids with AMR may reflect their suitability for rapid niche adaptation.Subject terms: Environmental microbiology, Genomics 相似文献
9.
A simian varicella virus (SVV) homolog to varicella-zoster virus gene 21 is expressed in monkey ganglia latently infected with SVV. 总被引:1,自引:1,他引:0 下载免费PDF全文
We have sequenced a simian varicella virus (SVV) open reading frame (ORF), 3,123 bp in length, whose product has 51% amino acid homology with the sequence encoded by the ORF of varicella-zoster virus gene 21. Several regions are highly conserved between the two ORFs, with homologies of approximately 80%. The SVV gene is transcribed in tissue culture cells productively infected with SVV and in monkey ganglia latently infected with SVV. 相似文献
10.