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51.
H. B. Nelson R. G. Heiman C. Bolduc G. E. Kovalick P. Whitley M. Stern K. Beckingham 《Genetics》1997,147(4):1783-1798
Calmodulin (CAM) is recognized as a major intermediary in intracellular calcium signaling, but as yet little is known of its role in developmental and behavioral processes. We have generated and studied mutations to the endogenous Cam gene of Drosophila melanogaster that change single amino acids within the protein coding region. One of these mutations produces a striking pupal lethal phenotype involving failure of head eversion. Various mutant combinations produce specific patterns of ectopic wing vein formation or melanotic scabs on the cuticle. Anaphase chromosome bridging is also seen as a maternal effect during the early embryonic nuclear divisions. In addition, specific behavioral defects such as poor climbing and flightlessness are detected among these mutants. Comparisons with other Drosophila mutant phenotypes suggests potential CAM targets that may mediate these developmental and behavioral effects, and analysis of the CAM crystal structure suggests the structural consequences of the individual mutations. 相似文献
52.
Laura Oksanen Miina Öhman Mark Heiman Katariina Kainulainen Jaakko Kaprio Pertti Mustajoki Veikko Koivisto Markku Koskenvuo Olli A. Jänne Leena Peltonen K. Kontula 《Human genetics》1997,99(5):559-564
Leptin, the product of the ob gene, reduces body fat in genetically obese animals and circulates in elevated concentrations in the blood of obese patients.
Polymorphic markers situated in the proximity of the human ob gene have recently been suggested to be linked to morbid obesity. We have studied the possible association between the microsatellite
markers near the ob gene and morbid obesity in 252 morbidly obese patients with a mean body mass index (BMI) of 43 ± 7 kg/m2, and 151 lean controls with a mean BMI of 22 ± 2 kg/m2, and searched for linkage of these gene markers to obesity in 76 affected sib-pairs (BMI ≥ 32). No significant association
was observed between any of the eight microsatellite markers and morbid obesity, and affected-sib-pair analysis failed to
show linkage of three selected ob gene markers to obesity in the sibships. There was a strong positive correlation between serum leptin levels and BMI in morbidly
obese patients; a carrier status for either of the two most prevalent alleles of the microsatellite marker D7S530 in the vicinity
of the ob gene was associated with serum leptin levels in the obese subjects. Two of the markers (D7S2519, D7S649) showed a significant
relation to the weight-losing response to a 16-week very-low-calorie dietary intervention. We have thus been able to confirm
a tight relationship between serum leptin and body mass but have found no evidence for genetic linkage of the ob gene markers to morbid obesity in a population considered to represent a genetic isolate and to be an ideal model for studies
of complex disorders.
Received: 25 October 1996 / Revised: 4 December 1996 相似文献
53.
MM El-Shazly El Elzayat IIA El-Sebeay YA Edmardash MM Soliman 《African Journal of Aquatic Science》2016,41(3):289-296
Manzala Lake, as one of the main Egyptian wetland ecosystems, is facing risks of pollution. An in vitro cytotoxicity test using a mammalian cell line was employed to determine the toxicity of multiple pollutants in the water and Tilapia zillii fish sampled from the lake. The concentrations of seven polychlorinated dibenzo-p-dioxins and ten polychlorinated dibenzofurans were investigated in water and muscle of the fish in 2014. Cytotoxicity testing showed that the percentage inhibition of cell viability in the studied sites ranged between 56.16% and 83.22%. Dioxin analysis indicated that the average concentrations of 1,2,3,4,6,7,8,9-octachlorodibenzo-p-dioxin, 1,2,3,4,7,8-hexachlorodibenzofuran, 1,2,3,4,6,7,8-heptachlorodibenzofuran and 1,2,3,4,6,7,8,9-octachlorodibenzofuran were higher than the toxic equivalence quotients (TEQs) set by the World Health Organization (WHO) in all water and fish muscle samples; however, the average concentration of 2,3,7,8-tetrachlorodibenzofuran was higher only in fish muscle samples. The bioaccumulation factor (BAF) ranged dramatically between 2 and 58.5 for the detected dioxins. Adverse human health effects through the consumption of fish are not expected, because dioxin levels in fish muscle are deemed safe for human consumption. Implementation of a strategic multidisciplinary action plan is strongly recommended to sustain this delta wetland ecosystem. 相似文献
54.
We investigated concentration-dependent primary and secondary substrate relationships in the simultaneous metabolism of the ubiquitous pollutant phenol and the naturally occurring substrate acetate by a Pseudomonas sp. soil isolate capable of utilizing either substance as a sole source of carbon and energy. In addition to conventional analytical techniques, solid-state 13C nuclear magnetic resonance spectroscopy was used to follow the cellular distribution of [1-13C]acetate in the presence of unlabeled phenol. With 5 mM acetate as the primary substrate, Pseudomonas sp. 9S8D2 removed 1 mM phenol (secondary substrate) at a rate of 2 nmol/mg of total cell protein. Although extensive acetate metabolism was indicated by a significant redistribution of the carboxyl label, this redistribution was not affected by the presence of phenol as a secondary substrate. When the primary and secondary substrate roles were reversed, however, the presence of 1 mM phenol altered the metabolism of 0.1 mM acetate, as evidenced by both the two- to fourfold increases in carboxyl label that appeared in terminal methyl and acyl chain methylene carbon resonances and the decrease in label that occurred in the carbohydrate spectral region. These results suggest that, when phenol is present as the primary substrate, acetate is preferentially shuttled into fatty acyl chain synthesis, whereas phenol carbon is funnelled into the tricarboxylic acid cycle. Thus, simultaneous use of a xenobiotic compound and a natural substrate apparently does occur, and the relative concentrations of the two substrates do influence the rate and manner in which the compounds are utilized.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
55.
56.
Sans résuméI. Analyse électrocapillaire des matières colorantes. Rev. gén. Mat. Col. 1926 Vol. 30 pp 34–45II. Phénomènes électrocapillaires et le problème du cancer. Arch. Med. Exper. 1926 Vol. I p 381III. Phénomènes électrocapillaires et l'antagonismes microbiens. Bol. Istituto Sier. Milano 1927 Vol. VI p 313. 相似文献
57.
In the companion paper (Holmquist et al. 1988), we concluded that there is
no agreement on either the correct branching order or differential rates of
evolution among the higher primates, and we examined in depth why this
uncertainty in the evolutionary understanding of our closest living
relatives persists. Recently, Lake developed two novel methods, based on
group properties of transition and transversion operators, that (a) permit,
in principle, objective resolution of problems of the above type and (b)
attach a statistical significance level to the conclusions drawn. In the
present paper, we develop formulas for using these two methods in tandem
and apply them to study transversion differences in (1) nuclear DNA for a
7-kb segment of the psi eta-globin locus and a 3-kb intergenic region
between the psi beta- and delta- globin loci and (2) mitochondrial DNA for
the 896-bp fragment of Brown et al. Although each of these nucleotide
sequence regions has its characteristic tempo and mode of evolution, the
nuclear and mitochondrial data together, comprising a total of 10,939 base
positions, support a Homo/Pan clade at the 97% confidence level. If we
calibrate the divergence point for humans and chimpanzees at 5 Myr,
consideration of the transversion branch lengths for the combined nuclear
data indicates that the gorilla lineage branched off 600,000- 900,000 years
prior to that, although the 2 sigma sampling errors do not preclude either
a temporal trifurcation for the three species or a considerably more
ancient branch point for the gorilla. To resolve the length of this central
branch to a relative accuracy of 25% and 30% will require a factor of 16
and nine times more data, respectively-- i.e., in excess of 100,000
homologous nucleotides for each of the four primates. For the nuclear
genes, heterogeneity in evolutionary rates between different parts of the
genome is mostly restricted to the human lineage for these two segments.
The lineage leading to chimpanzees has evolved 0.4 (3-kb fragment) to 3.5
(7-kb segment) times as rapidly as the lineage leading to humans, and that
leading to the gorilla has evolved approximately one-fifth to one-half as
rapidly as that leading to chimpanzees. Thus, even local molecular clocks
can "tick" badly. As significant is the fact that virtually contiguous
parts of the genome tick at markedly different rates.(ABSTRACT TRUNCATED AT
400 WORDS)
相似文献
58.
Purified rat mast cells were used to study the effects of anti-inflammatory steroids on the release of [1-14C]-arachidonic acid ([1-14C]AA) and metabolites. Mast cells were incubated overnight with glucocorticoids, [1-14C]AA incorporated into cellular phospholipids and the release of [1-14C]AA, and metabolites determined using a variety of secretagogues. Release of [1-14C]AA and metabolites by concanavalin A, the antigen ovalbumin and anti-immunoglobulin in E antibody was markedly reduced by glucocorticoid treatment. Neither the total incorporation of [1-14C]AA nor the distribution into phospholipids was altered by hydrocortisone pretreatment. Glucocorticoid pretreatment did not alter [1-14C]AA release stimulated by somatostatin, compound 48/80, or the calcium ionophore, A23187. These data indicate that antiinflammatory steroids selectively inhibit immunoglobulin dependent release of arachidonic acid from rat mast cells. These findings question the role of lipomodulin and macrocortin as general phospholipase inhibitors and suggest that they may be restricted to immunoglobulin stimuli. 相似文献
59.
60.
Summary Continuous water flow and static test apparatus were used in evaluating the influence of acclimation temperature, size, sex, season, life stage, current velocity, and testing method upon the upper-lethal temperature of the nymphal stage of the stonefly, Paragnetina media Walker.Lethal temperature was raised by acclimation to higher temperatures throughout the thermal range examined. The rate of gain of heat resistance was approximately 5°C per day. Acclimation to colder temperatures was much slower.Body size had no significant effect on upper-lethal temperature in summer or autumn, whereas in winter and spring larger nymphs were significantly less tolerant than smaller nymphs. This difference was attributed to sex, not body size per se.Tolerance was significantly less in static waters than in flowing water, faster current significantly increasing heat resistance at all lethal temperatures examined.Upper-lethal temperatures showed seasonal differences independent of acclimation, with nymphs least tolerant in spring, when temperature resistance was influenced by sex, molting condition, and proximity of emergence. The most temperature-sensitive stage was the period immediately following egg hatching.The direct effect of upper-lethal temperature is apparently not a limiting factor for P. media in the environment in which it is found. Temperature increases do, however, effect final stages of nymphal development, emergence patterns, and survival after hatching.Contribution No. 213, W. K. Kellogg Biological Station of Michigan State University. This investigation was supported in part by Research Grant WP 01178 from the Federal Water Pollution Control Administration. 相似文献