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131.
Microsatellite variation in Drosophila melanogaster and Drosophila simulans: a reciprocal test of the ascertainment bias hypothesis 总被引:2,自引:1,他引:1
Interspecific comparisons of microsatellite loci have repeatedly shown that
the loci are longer and more variable in the species from which they are
derived (the focal species) than are homologous loci in other (nonfocal)
species. There is debate as to whether this is due to directional evolution
or to an ascertainment bias during the cloning and locus selection
processes. This study tests these hypotheses by performing a reciprocal
study. Eighteen perfect dinucleotide microsatellite loci identified from a
Drosophila simulans library screen and 18 previously identified in an
identical Drosophila melanogaster library screen were used to survey
natural populations of each species. No difference between focal and
nonfocal species was observed for mean PCR fragment length. However,
heterozygosity and number of alleles were significantly higher in the focal
species than in the nonfocal species. The most common allele in the
Zimbabwe population of both species was sequenced for 31 of the 36 loci.
The length of the longest stretch of perfect repeat units is, on average,
longer in the focal species than in the non-focal species. There is a
positive correlation between the length of the longest stretch of perfect
repeats and heterozygosity. The difference in heterozygosity can thus be
explained by a reduction in the length of the longest stretch of perfect
repeats in the nonfocal species. Furthermore, flanking-sequence length
difference was noted between the two species at 58% of the loci sequenced.
These data do not support the predictions of the directional-evolution
hypothesis; however, consistent with the ascertainment bias hypothesis, the
lower variability in nonfocal species is an artifact of the microsatellite
cloning and isolation process. Our results also suggest that the magnitude
of ascertainment bias for repeat unit length is a function of the
microsatellite size distribution in the genomes of different species.
相似文献
132.
Summary The development of the tissue culture technique has enabled us to cultivate mammalian cells in a way which is similar to that in use with bacterial cells. As such, the nutritional requirements of mammalian cells in culture have been studied with simplicity and exactness. According to Eagle's extensive works it is accepted that cultured cells generally require 13 amino acids, 8 or 9 vitamins, glucose and 6 inorganic salts. However, although some cultured cells have a capacity for the biosynthesis of Eagle's essential nutrients and others require non-essential nutrients.In this review we will discuss the amino acid and vitamin requirements of cultured cells, and a cell line (R-Y121B · cho) which propagates continuously in a chemically defined medium containing 11 amino acids, 7 vitamins, glucose and 6 ionic salts. Arginine, glutamine, tyrosine and choline are synthesized in the R-Y121B · cho cells. 相似文献
133.
Mark Ming-Long Hsu MD Jen-Chyi Chang Koji Yokoyama Kazuko Nishimura Makoto Miyaji 《Mycopathologia》1994,127(2):77-81
Twenty-one strains ofCryptococcus neoformans isolated from patients in Taiwan were characterized for serotypes and mating types. Slide agglutination test was performed with 8 factor-specific sera (Iatron Company, Japan) to determine the serotypes. Wheat bran agar (WBA) and malt extract agar (MEA, Wickerham) media were used for the mating tests. Twenty of the isolates were of serotype A, and one was serotype B. Except for 2 strains of serotype A, all of the serotype A strains mated withFilobasidiella neoformans var.neoformans, mating type a. The only serotype B strain mated withF. neoformans var.bacillispora mating type a in MEA medium. These data revealed the low prevalence (1/21; 4.8%) ofC. neoformans var.gattii in Taiwan, a subtropically located island. 相似文献
134.
In vitro and in vivo antifungal activities of liposomal amphotericin B,and amphotericin B lipid complex 总被引:1,自引:0,他引:1
Kotaro Mitsutake Shigeru Kohno MD Yoshitsugu Miyazaki Tetsuhiro Noda Haruko Miyazaki Takashige Miyazaki Mitsuo Kaku Hironobu Koga Kohei Hara 《Mycopathologia》1994,128(1):13-17
The in vitro and in vivo antifungal activities of liposomal amphotericin B (L-AMPH) and amphotericin B lipid complex (ABLC), which is composed of amphotericin B and the phospholipids dimyristoyl phosphatidylcholine and dimyristoyl phosphatidylglycerol, were compared with those of conventional amphotericin B (Fungizone®, AMPH). The acute intravenous toxicity was markedly lower in BALB/c mice; 50% lethal doses (LD50s) were 2.75 mg/kg in AMPH, 32.9 mg/kg in L-AMPH and >75 mg/kg in ABLC. In vitro antifungal activities againstCandida albicans, C. parapsilosis, C. tropicalis, C. glabrata, andC. krusei were evaluated by the agar plate dilution method. The activities were unchanged againstC. albicans, but MICs increased more than four fold in 18 of the 20 strains other thanC. albicans in L-AMPH and in 9 of the 20 in ABLC. L-AMPH and ABLC were as efficacious as AMPH in the treatment of mice infected withC. albicans, and at a dose of 0.5 and 1.0 mg/kg of body weight, ABLC was more efficacious on survival. A ten-times larger dose (10 mg/kg) of L-AMPH and ABLC was administered to mice with 100% survival, suggesting improved tolerability as compared to amphotericin B. 相似文献
135.
Myocardial ischemia-reperfusion (I/R) is associated with the activation of matrix metalloproteinases (MMPs) and serine proteases. We hypothesized that activation of MMPs and the serine protease plasmin contribute to early cardiac myocyte death following I/R and that broad-spectrum protease inhibition with doxycycline (DOX) preserves myocyte viability. Rats treated daily with or without DOX beginning 48 h prior to experimentation were subjected to 30 min of coronary occlusion and 2 days of reperfusion. DOX pre-treatment reduced infarct size by 37%. DOX attenuated increases in MMP-9 and plasmin levels as determined by gelatin zymography and immunoblot, respectively. Neutrophil extravasation was unaltered by DOX as assessed by myeloperoxidase (MPO) activity. To examine the contribution of MMP-9 and plasmin to myocyte injury, cultures of neonatal rat ventricular myocytes (NRVMs) were treated for 48 h with 83 kDa MMP-9 or plasminogen in the presence or absence of DOX. MMP-9 treatment did not affect myocyte viability. Plasminogen treatment led to increased plasmin activity, resulting in loss of 1-integrin, NRVM detachment and apoptosis. DOX co-treatment inhibited plasmin activity and preserved NRVM attachment, whereas co-treatment with the broad-spectrum MMP inhibitor GM6001 had no effect. These results indicate that plasmin causes disruption of myocyte attachment and viability independently of MMP activation in vitro and that inhibition of plasmin by DOX may reduce I/R-induced myocyte death in vivo through the inhibition of plasmin. (Mol Cell Biochem 270: 1–11, 2005) 相似文献
136.
Recent work defines coevolution between plants and herbivores as pairwise when the pattern of selection on resistance traits and the response to selection are both independent of the presence or absence of other herbivores. In addition, for a pairwise response to selection, resistance to a focal herbivore must have the same genetic basis in the presence and absence of other herbivores. None of these conditions were satisfied for the ivyleaf morning glory, Ipomoea hederacea, and its insect, fungal, and mammalian natural enemies with a quantitative genetics field experiment. A significant negative genetic correlation exists between resistance to deer and generalist insect herbivory that would preclude an independent response to selection. In addition, resistance loci under selection differ depending on the composition of the natural enemy community as indicated by genetic correlations between deer resistances in the presence and absence of other natural enemies that differ substantially from 1. Finally, selection on deer resistance depends on the presence or absence of insects; in the presence of insects, greater deer resistance is favored, but in the absence of insects, deer resistance is effectively neutral. These results indicate that the composition of the natural enemy community can alter both the pattern of selection and the likely response to selection of resistance traits. 相似文献
137.
Negin Rezavand MD Saba Tabarok MD Ziba Rahimi MSc Asad Vaisi-Raygani PhD Ehsan Mohammadi MSc Zohreh Rahimi PhD 《Journal of cellular biochemistry》2019,120(4):6441-6448
We investigated the influence of vitamin D receptor (VDR) polymorphisms and vitamin D level on the blood pressure and the risk of preeclampsia. In a case-control study, 200 pregnant women, including 100 individuals with preeclampsia along with 100 healthy pregnant women, were studied for VDR FokI, TaqI, and BmsI polymorphisms and serum 25 (OH)-D level using polymerase chain reaction-restriction fragment length polymorphism method and commercial kit, respectively. The mean level of 25 (OH)-D in preeclamptic patients was significantly lower (16.6 ± 4.2 ng/mL, P < 0.001) compared with controls (19.6 ± 3.8 ng/mL). Among all women, a significantly higher systolic blood pressure and before-pregnancy body mass index and also lower gestational age were observed in the presence of 25 (OH)-D level < 20 ng/mL compared with the 20 to 30 ng/mL. A significantly higher frequency of VDR FokI C allele in preeclamptic patients (83%) than controls (74%) was associated with a 1.72-fold increased risk of preeclampsia. In all the studied individuals, the systolic and diastolic blood pressures were significantly higher in the presence of the FokI CC genotype compared with the TC and TT+TC genotypes. Neither VDR Taq1 nor VDR BmsI was associated with the risk of preeclampsia. The haplotype FokI C, TaqI C and BmsI A (CCA) compared with haplotype CTG increased the risk of preeclampsia by 1.4-fold (P = 0.33). Our study suggests an association between VDR FokI polymorphism and an insufficient serum level of 25 (OH)-D with the risk of preeclampsia and also the influence of insufficient 25 (OH)-D level and VDR FokI polymorphism on maternal factors, including blood pressure. 相似文献
138.
139.
Studies of induced plant resistance usually either examine physiological/chemical mechanisms or explore the ecological and evolutionary role of induced resistance. To connect these two methods of study, data are needed that address the relationships between plant chemistry and effects of induced resistance on herbivores under field conditions. In this paper we combine the results of a greenhouse experiment and a field experiment to try to make such a connection. Levels of induced and constitutive resistance to Mexican bean beetles in several soybean genotypes were measured in a greenhouse experiment using a behavioral bioassay. In a field experiment, beetle performance and induced and constitutive levels of cystein proteinase inhibitor activity were measured for these same genotypes. Greenhouse bioassay ratings of induced and constitutive resistance and induced and constitutive levels of proteinase inhibitor activity agree closely for individual genotypes, suggesting that proteinase inhibitors (PIs) are involved in induced resistance. However, while greenhouse bioassay measures of constitutive and induced resistance were good predictors of beetle performance in the field, proteinase inhibitor activity did not predict beetle performance well. While PIs appear to be involved in induced resistance, they were not strongly correlated to Mexican bean beetle performance in the field in this study. These results suggest that measurement of single aspects of plant chemistry may not encompass all ecologically important aspects of plant resistance. 相似文献
140.