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Pinson DM 《Lab animal》2011,40(6):187-192
Although IACUC-related topics are frequently discussed in the literature, there is little published information about how to write animal activity proposals. In this article, the author discusses key considerations in the writing and review of animal activity proposals. The author then describes a framework for developing and writing clear animal activity proposals that highlight animal welfare concerns. Though these recommendations are aimed at individuals writing and reviewing research proposals, the framework can be modified for other types of animal activity proposals. 相似文献
74.
Ribosomal RNA secondary structure: compensatory mutations and implications for phylogenetic analysis 总被引:6,自引:0,他引:6
Using sequence data from the 28S ribosomal RNA (rRNA) genes of selected
vertebrates, we investigated the effects that constraints imposed by
secondary structure have on the phylogenetic analysis of rRNA sequence
data. Our analysis indicates that characters from both base-pairing regions
(stems) and non-base-pairing regions (loops) contain phylogenetic
information, as judged by the level of support of the phylogenetic results
compared with a well-established tree based on both morphological and
molecular data. The best results (the greatest level of support of
well-accepted nodes) were obtained when the complete data set was used.
However, some previously supported nodes were resolved using either the
stem or loop bases alone. Stem bases sustain a greater number of
compensatory mutations than would be expected at random, but the number is
< 40% of that expected under a hypothesis of perfect compensation to
maintain secondary structure. Therefore, we suggest that in phylogenetic
analyses, the weighting of stem characters be reduced by no more than 20%,
relative to that of loop characters. In contrast to previous suggestions,
we do not recommend weighting of stem positions by one-half, compared with
that of loop positions, because this overcompensates for the constraints
that selection imposes on the secondary structure of rRNA.
相似文献
75.
Pinson SE Parr CM Wilson JL Navara KJ 《Physiological and biochemical zoology : PBZ》2011,84(3):292-298
Birds have demonstrated a remarkable ability to manipulate offspring sex. Previous studies suggest that treatment with hormones can stimulate females to manipulate offspring sex before ovulation. For example, chronic treatments with corticosterone, the primary stress hormone produced by birds, stimulated significant skews toward female offspring. It has been suggested that corticosterone acts by influencing which sex chromosome is donated by the heterogametic female bird into the ovulated ovarian follicle. However, it is difficult to pinpoint when in developmental time corticosterone affects offspring sex, because in previous studies corticosterone treatment was given over a long period of time. We treated laying hens with acute high-dose corticosterone injections 5 h before the predicted time of ovulation and quantified the sexes of the subsequently ovulated eggs to determine whether mechanisms exist by which corticosterone can skew offspring sex ratios just before ovulation. We hypothesized that an injection of corticosterone coincident with segregation of the sex chromosomes would stimulate hens to produce more female than male offspring. Contrary to our predictions, hens injected with corticosterone produced a significant bias toward male offspring, nearly 83%. These results suggest that acute corticosterone treatment during meiosis I can influence primary sex ratios in birds, potentially through nonrandom chromosome segregation. Furthermore, acute corticosterone exposure, compared with chronic exposure, may act through different mechanisms to skew offspring sex. 相似文献
76.
Cell division and development are regulated by networks of kinases and phosphatases. In early Drosophila embryogenesis, 13 rapid nuclear divisions take place in a syncytium, requiring fine coordination between cell cycle regulators. The Polo kinase is a conserved, crucial regulator of M-phase. We have recently reported an antagonism between Polo and Greatwall (Gwl), another mitotic kinase, in Drosophila embryos. However, the nature of the pathways linking them remained elusive. We have conducted a comprehensive screen for additional genes functioning with polo and gwl. We uncovered a strong interdependence between Polo and Protein Phosphatase 2A (PP2A) with its B-type subunit Twins (Tws). Reducing the maternal contribution of Polo and PP2A-Tws together is embryonic lethal. We found that Polo and PP2A-Tws collaborate to ensure centrosome attachment to nuclei. While a reduction in Polo activity leads to centrosome detachments observable mostly around prophase, a reduction in PP2A-Tws activity leads to centrosome detachments at mitotic exit, and a reduction in both Polo and PP2A-Tws enhances the frequency of detachments at all stages. Moreover, we show that Gwl antagonizes PP2A-Tws function in both meiosis and mitosis. Our study highlights how proper coordination of mitotic entry and exit is required during embryonic cell cycles and defines important roles for Polo and the Gwl-PP2A-Tws pathway in this process. 相似文献
77.
78.
Reproductive energy expenditure and changes in body morphology for a population of Chinook salmon Oncorhynchus tshawytscha with a long distance migration 总被引:1,自引:0,他引:1 下载免费PDF全文
T. E. Bowerman A. Pinson‐Dumm C. A. Peery C. C. Caudill 《Journal of fish biology》2017,90(5):1960-1979
Energetic demands of a long freshwater migration, extended holding period, gamete development and spawning were evaluated for a population of stream‐type Chinook salmon Oncorhynchus tshawytscha. Female and male somatic mass decreased by 24 and 21%, respectively, during migration and by an additional 18 and 12% during holding. Between freshwater entry and death after spawning, females allocated 14% of initial somatic energy towards gonad development and 78% for metabolism (46, 25 and 7% during migration, holding and spawning, respectively). Males used only 2% of initial somatic energy for gonad development and 80% on metabolic costs, as well as an increase in snout length (41, 28 and 11% during migration, holding and spawning, respectively). Individually marked O. tshawytscha took between 27 and 53 days to migrate 920 km. Those with slower travel times through the dammed section of the migration corridor arrived at spawning grounds with less muscle energy than faster migrants. Although energy depletion did not appear to be the proximate cause of death in most pre‐spawn mortalities, average final post‐spawning somatic energy densities were low at 3·6 kJ g?1 in females and 4·1 kJ g?1 in males, consistent with the concept of a minimum energy threshold required to sustain life in semelparous salmonids. 相似文献
79.
TT Chowdhury S Arghandawi J Brand OO Akanji DL Bader DM Salter DA Lee 《Arthritis research & therapy》2008,10(2):R35
Background
Nitric oxide and prostaglandin E2 (PGE2play pivotal roles in both the pathogenesis of osteoarthritis and catabolic processes in articular cartilage. These mediators are influenced by both IL-1β and mechanical loading, and involve alterations in the inducible nitric oxide synthase (iNOS) and cyclo-oxygenase (COX)-2 enzymes. To identify the specific interactions that are activated by both types of stimuli, we examined the effects of dynamic compression on levels of expression of iNOS and COX-2 and involvement of the p38 mitogen-activated protein kinase (MAPK) pathway. 相似文献80.
The complexity of genetic pathways for hearing is beginning to be amenable to unraveling by systematic functional genomic analysis. Genome-wide mutagenesis studies in the mouse are beginning to shed further light on the structure and regulation of the machinery of hearing. 相似文献