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1.
Nielsen J; Peixoto AA; Piccin A; Costa R; Kyriacou CP; Chalmers D 《Molecular biology and evolution》1994,11(6):839-853
The region of the clock gene period (per) that encodes a repetitive tract
of threonine-glycine (Thr-Gly) pairs has been compared between Dipteran
species both within and outside the Drosophilidae. All the non-
Drosophilidae sequences in this region are short and present a remarkably
stable picture compared to the Drosophilidae, in which the region is much
larger and extremely variable, both in size and composition. The
accelerated evolution in the repetitive region of the Drosophilidae appears
to be mainly due to an expansion of two ancestral repeats, one encoding a
Thr-Gly dipeptide and the other a pentapeptide rich in serine, glycine, and
asparagine or threonine. In some drosophilids the expansion involves a
duplication of the pentapeptide sequence, but in Drosophila pseudoobscura
both the dipeptide and the pentapeptide repeats are present in larger
numbers. In the nondrosophilids, however, the pentapeptide sequence is
represented by one copy and the dipeptide by two copies. These observations
fulfill some of the predictions of recent theoretical models that have
simulated the evolution of repetitive sequences.
相似文献
2.
Evolutionary origin of human and primate malarias: evidence from the circumsporozoite protein gene 总被引:8,自引:1,他引:7
We have analyzed the conserved regions of the gene coding for the
circumsporozoite protein (CSP) in 12 species of Plasmodium, the malaria
parasite. The closest evolutionary relative of P. falciparum, the agent of
malignant human malaria, is P. reichenowi, a chimpanzee parasite. This is
consistent with the hypothesis that P. falciparum is an ancient human
parasite, associated with humans since the divergence of the hominids from
their closest hominoid relatives. Three other human Plasmodium species are
each genetically indistinguishable from species parasitic to nonhuman
primates; that is, for the DNA sequences included in our analysis, the
differences between species are not greater than the differences between
strains of the human species. The human P. malariae is indistinguishable
from P. brasilianum, and P. vivax is indistinguishable from P. simium; P.
brasilianum and P. simium are parasitic to New World monkeys. The human P.
vivax-like is indistinguishable from P. simiovale, a parasite of Old World
macaques. We conjecture that P. malariae, P. vivax, and P. vivax-like are
evolutionarily recent human parasites, the first two at least acquired only
within the last several thousand years, and perhaps within the last few
hundred years, after the expansion of human populations in South America
following the European colonizations. We estimate the rate of evolution of
the conserved regions of the CSP gene as 2.46 x 10(-9) per site per year.
The divergence between the P. falciparum and P. reichenowi lineages is
accordingly dated 8.9 Myr ago. The divergence between the three lineages
leading to the human parasites is very ancient, about 100 Myr old between
P. malariae and P. vivax (and P. vivax-like) and about 165 Myr old between
P. falciparum and the other two.
相似文献
3.
H. Brandsch A. E. H. Kadry 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1977,51(3):119-125
Summary The cross-nursing technique was used to assess the relative importance of prenatal and postnatal maternal influences on growth in mice from an unselected population originated from a cross of four highly inbred strains. Body weights were studied at birth, 7-, 14-, 21- and 42-days, in addition to the weight gains between these ages and tail length at 21 and 42 days of age. At littering, each dam in each nursing set retained two of her own offspring and two were transfereed to each of the other dams in the set, so that each nursed litter contained six young representing three mothers. Prenatal influences accounted for 37, 15, 10, 11 and 13 % of the total variation in the respective body weights, while postnatal influences accounted for 0, 64, 65, 49 and 14% at the respective ages. In the case of weight gains, prenatal influences were responsible for 16, 4, 6 and 30%, while postnatal influences were responsible for 66, 66, 31 and 7% of the total variation in gain during the respective four periods examined. Apparently the individual weight gain from 7 to 14 days was a better measure of the lactational performance of the dam than individual 14-day weight. For tail length, prenatal influences accounted for 6 % and 4 % of the total variation in tail length at 21 and 42 days, respectively, while postnatal influences accounted for 60 % and 24 % at the respective ages. Generally, there was no indication of an important interaction between the nurse and the nursed young at any stage studied. 相似文献
4.
Photosynthetic enhancement studies performed at 619 nm (excitation of Systems I and II) and at 446 nm (mainly excitation of System I) revealed an 18% photosynthetic enhancement simultaneously with a 31% reduction in glycolate excretion. This observation supports the hypothesis that some glycolate may be consumed in an oxidation process associated with System I when System II is poorly excited and the supply of electrons from the water splitting process of photosynthesis is low. 相似文献
5.
The anabolic action of intermittent parathyroid hormone on cortical bone depends partly on its ability to induce nitric oxide‐mediated vasorelaxation in BALB/c mice
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S Gohin A Carriero C Chenu AA Pitsillides TR Arnett M Marenzana 《Cell biochemistry and function》2016,34(2):52-62
There is strong evidence that vasodilatory nitric oxide (NO) donors have anabolic effects on bone in humans. Parathyroid hormone (PTH), the only osteoanabolic drug currently approved, is also a vasodilator. We investigated whether the NO synthase inhibitor L‐NAME might alter the effect of PTH on bone by blocking its vasodilatory effect. BALB/c mice received 28 daily injections of PTH[1–34] (80 µg/kg/day) or L‐NAME (30 mg/kg/day), alone or in combination. Hindlimb blood perfusion was measured by laser Doppler imaging. Bone architecture, turnover and mechanical properties in the femur were analysed respectively by micro‐CT, histomorphometry and three‐point bending. PTH increased hindlimb blood flow by >30% within 10 min of injection (P < 0.001). Co‐treatment with L‐NAME blocked the action of PTH on blood flow, whereas L‐NAME alone had no effect. PTH treatment increased femoral cortical bone volume and formation rate by 20% and 110%, respectively (P < 0.001). PTH had no effect on trabecular bone volume in the femoral metaphysis although trabecular thickness and number were increased and decreased by 25%, respectively. Co‐treatment with L‐NAME restricted the PTH‐stimulated increase in cortical bone formation but had no clear‐cut effects in trabecular bone. Co‐treatment with L‐NAME did not affect the mechanical strength in femurs induced by iPTH. These results suggest that NO‐mediated vasorelaxation plays partly a role in the anabolic action of PTH on cortical bone. © 2016 The Authors. Cell Biochemistry and Function published by John Wiley & Sons, Ltd. 相似文献
6.
AA Smith 《Biotechnic & histochemistry》2016,91(6):396-400
One can determine the best dilution of a primary antibody for immunohistochemistry that uses horseradish peroxidase conjugated to a secondary antibody by testing increasing concentrations sequentially on the same tissue section. When the same tissue section is incubated repeatedly with increasing concentrations of primary antibodies to epithelial membrane antigen, smooth muscle α-actin, or vimentin using alkaline phosphatase conjugated to a secondary antibody as the reporter, the best staining was obtained with a less concentrated primary antibody than was optimal for a single staining test. The best concentration of primary antibody for single run staining using an alkaline phosphatase reporting system is usually four times the best concentration for staining with multiple runs. The optimal concentration can be determined by denaturing the residual alkaline phosphatase and extracting residual stain by incubating the section in 4:1 diglyme:phosphate buffered saline for 20 min at 80o C between tests of primary antibody concentrations. I tested the method for four chromogens from one supplier and one chromogen from a different supplier. 相似文献
7.
Sara M Mohamed Emam A Abdel-Rahim Tahany AA Aly AbdelMoneim M Naguib Marwa S Khattab 《Experimental biology and medicine (Maywood, N.J.)》2022,247(5):385
Increased environmental pollution and unhealthy lifestyle are blamed for escalated chronic diseases. Exposure to aflatoxins was recently suggested to have a role in the increased incidence of type 2 diabetes mellitus. Diet modification and consumption of different functional food are now gaining attention, especially in diabetes management. This study investigates the effect of a diet containing barley microgreen against diabetes induced by streptozotocin with or without aflatoxin administration in rats. Barley microgreen was rich in 3′-Benzyloxy-5,6,7,4′-tetramethoxyflavone (48.8% of total) followed by 5β,7βH,10α-Eudesm-11-en-1α-ol (18.46%). Streptozotocin injection and/or aflatoxin administration significantly elevated glucose level, decreased insulin level, decreased β-cell function, deteriorated liver and kidney function parameters, and induced oxidative stress in the liver. Histopathology revealed irregular small-sized islets and decreased area % of insulin-positive beta cells in the pancreas, hepatic degeneration, nephropathy, and neuropathy in diabetic and/or aflatoxin administered rats compared to control. Barley microgreen diet fed to diabetic rats with or without aflatoxin alleviated all evaluated parameters. Barley microgreen diet also ameliorated the toxic effect of aflatoxin. In conclusion, exposure to aflatoxin aggravated diabetes and its complication. The incorporation of barley microgreen in the diet was able to control type 2 diabetes mellitus and the improved outcomes observed with barley microgreen treatments involved or occurred in conjunction with improved biomarkers of oxidative stress. 相似文献
8.
Serry FM Kadry AA Abdelrahman AA 《Journal of industrial microbiology & biotechnology》2003,30(3):135-140
The present study aimed to isolate, select, and evaluate bacterial isolates with potential for use as biological indicators
for sterilization with glutaraldehyde and/or formaldehyde. A total of 340 local Bacillus isolates were screened for glutaraldehyde and/or formaldehyde resistance by determination of minimum inhibitory concentrations
(MICs), minimum bactericidal concentrations (MBCs), and extinction time and were compared with B. subtilis (var. niger) ATCC 9372, the biological indicator for ethylene oxide sterilization, as reference. Of these, 85 isolates had glutaraldehyde
MICs of 0.5% or higher, while 29 had formaldehyde MICs of 0.04% or higher. Of the 29 resistant isolates, 15 had MBCs of 0.05%
or more. Extinction times were used to evaluate the bactericidal/sporicidal activity of glutaraldehyde. Eight had inactivation
times of more than 5 h in 2% glutaraldehyde (pH 8), whereas 12 had inactivation times of more than 3 h in l% formaldehyde,
with one isolate in common. These 19 isolates were selected and evaluated as potential biological indicators for aldehydes
by determination of the decimal reduction times (D values), compared with the reference strain. Eight glutaraldehyde-resistant isolates exhibited D values 2.0- to 3.5-fold higher than the reference strain (30 min.). Only five of 12 formaldehyde resistant isolates had D values higher than that of the reference strain. Using six resistant isolates, temperature coefficient values between 2.11 and
3.02 were obtained for 2% formaldehyde. Finally, 14 isolates were tested for potential pathogenicity and were identified to
species level. All of the eight glutaraldehyde-resistant isolates, including the isolate with dual resistance, and three formaldehyde-resistant
isolates were B. licheniformis, while two other formaldehyde-resistant isolates were B. cereus. Six of the selected B. licheniformis isolates are potential biological indicators for sterilization processes using aldehydes. Three can be suggested for glutaraldehyde
only and three for both aldehydes.
Electronic Publication 相似文献
9.
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