Pegasus, a small terminal inverted repeat transposable element found in the white gene of Anopheles gambiae

Pegasus, a novel transposable element, was discovered as a length polymorphism in the white gene of Anopheles gambiae. Sequence analysis revealed that this 535 bp element was flanked by 8 bp target site duplications and 8 bp perfect terminal inverted repeats similar to those found in many members of the Tcl family. Its small size and lack of long open reading frames preclude protein coding capacity. Southern analysis and in situ hybridization to polytene chromosomes demonstrated that Pegasus occurs in approximately 30 copies in the genomes of An. gambiae and its sibling species and is homogenous in structure but polymorphic in chromosomal location. Characterization of five additional elements by sequencing revealed nucleotide identities of 95% to 99%. Of 30 Pegasus-containing phage clones examined by PCR, only one contained an element exceeding 535 bp in length, due to the insertion of another transposable element-like sequence. Thus, the majority, if not all, extant Pegasus elements may be defective copies of a complete element whose contemporary existence in An. gambiae is uncertain. No Pegasus-hybridizing sequences were detected in nine other anophelines and three culicines examined, suggesting a very limited taxonomic distribution.     

Protein polymorphism inEligmodontia typus. Genetic divergence with other phyllotine cricetids

By means of gel electrophoresis of tissue extracts we have studied protein polymorphism inEligmodontia typus. The analysis was performed on specimens from five population samples collected at different sites in Patagonia (Argentina). Mean heterozygosity (\-h) and proportion of polymorphic loci (P) were determined on the basis of 19 loci. Considering all individuals as one sample, \-h gave a value of 0.16 and P was 70%. Although these values are much higher than those reported for most rodent species, they are very similar to those obtained by us for four species of the genusCalomys and forGraomys griseoflavus. There is a striking genetic identity (I_N=0.99) among populations from regions with different environmental conditions, indicating that the species possesses a common genic pool. Genetic distance with other species of the Phyllotini was estimated. D_N was lower betweenE. typus andCalomys (mean D_N=0.88) than betweenE. typus andGraomys griseoflavus (D_N=1.01). The high morphological similarity between these last two species, especially regarding those characters related to desert life adaptation, could be assigned, at least in part, to convergent evolution.     

Hemoglobin in Chironomus ramosus (Insecta, Diptera): an electrophoretic study of polymorphism, developmental sequence and interspecific relationship

The larvae of the dipteran insect, Chironomus ramosus, found in Shillong, India, contain eleven (11) hemoglobin (Hb) components of which three are monomers (CI, CIV and CVI) and seven are dimers (CIII, CV, CVII, CVIII, CIX, CX and CXI), while one (CII) exists in both monomeric and dimeric states.Four monomeric components were isolated, purified and partially characterized. The N-terminal amino acids were determined and showed glycine for CI and leucine for the other components (CII, CIV and CVI).Three hemoglobin components were found to be present in all stages of larval development, except the first instar larvae. Some Hb components were synthesized in a particular instar, as revealed by electrophoretic appearance.Electrophoretic mobilities of seven components and N-terminal amino acid residues of two components of Hb were similar in both Chironomus ramosus and Chironomus thummi thummi.     

Transformation of the extremely thermoacidophilic archaeon Sulfolobus solfataricus via a self-spreading vector

Abstract The comparative chromosomal locations of polymeric β-fructosidase SUC genes have been determined by Southern blot hybridization with the SUC2 probe in 91 different strains of Saccharomyces cerevisiae . Most of the strains exhibited a single SUC2 gene, but in some strains two or three SUC genes were found. All Suc⁻ strains carried a silent suc2⁰ sequence. The accumulation of SUC genes was observed in populations derived from sources containing sucrose and seems to be absent in strains from sources promoting the MEL gene.     

温度对粘虫产生和释放性信息素规律的影响

在21℃饲养的粘虫雌蛾腺体提取物中Zll－16：Aid含量峰值时间是羽化后第8～9天;25℃是羽化后第4～5天,27℃是羽化后第3～4天。低温不仅推迟了粘虫雌蛾求偶和释放性信息素的时间,而且降低了腺体中性信息素的滴度。在27℃,粘虫雌蛾腺体中Zll－16：Ald峰值的平均值达15ng;在25℃时为10ng,而在21℃时,只有5ng。由此可见,低温环境明显抑制粘虫雌蛾的性发育,延缓了性成熟。     

小麦与玉米及鸭茅状摩擦禾远缘杂交的胚发育过程中同工酶和蛋白质的变化

通过比较小麦与玉米及鸭茅状摩擦禾属间杂交获得的胚与小麦正常自交的胚之间在不同发育时期过氧化物酶和酯酶的同工酶谱,发现过氧化物酶同工酶表现出时空顺序的特异性变化。在同一发育时期,远缘杂交的具胚子房和无胚子房之间存在过氧化物酶同工酶谱的差异,这可能涉及到与胚发育相关的同工酶的出现。远缘杂交的具胚子房和正常自交的小麦子房之间也有一定的酶谱差异。同时,同一材料还表现出不同发育时期的过氧化物酶酶谱差别。在远缘杂交后的胚发育期间,酯酶同工酶的时空表达不如过氧化物酶显著。此外,对远缘杂交后的胚中的水溶性蛋白质进行了SD S-PAGE分析,初步的分析结果表明,可能存在与胚发育相关的蛋白质。     

Anatomical distribution of NADPH-cytochrome P450 reductase and cytochrome P4502D forms in rat brain: Effects of xenobiotics and sex steroids

Since the brain is not a homogeneous organ, but one dependent upon the well orchestrated interaction of numerous parts, pathology in one nucleus may have a large impact upon its overall function. Hence, the anatomical distribution of the P450 monoxygenase system in brain, as well as the regulation of its expression, is important in elucidating its function in that organ. In order to study these issues, female rats-both ovariectomized and not-were treated with a number of xenobiotic compounds and sex steroids. The brains from these animals were dissected into 8 discrete regions and the presence and relative level of message for P4502D and P450 reductase determined using polymerase chain reaction. Results of this investigation indicate the presence of mRNA for reductase and P4502D isoforms throughout the rat brain. In addition, quantitative PCR was utilized to demonstrate the effects of xenobiotics (phenobarbital, β-naphthoflavone, imipramine) and sex hormones (testosterone, estrogen) on the levels of these messages in the female rat brain. Significant induction of message for P4502D forms was noted with testosterone in the absence of estrogen. The level of mRNA for reductase was not significantly influenced by any of the treatments, however. These results raise the issue of a sexual dimorphism in the rat regarding P4502D expression in brain.     

Use of chicken microsatellite markers in turkey: a pessimistic view

Eighty-eight chicken microsatellite markers, previously developed in our laboratory, were tested for their ability to amplify polymorphic fragments using turkey genomic DNA. Amplification products were obtained for 61 chicken microsatellite markers (69.1%) whereas 27 (30.9%) did not give rise to any products, even when different polymerase chain reaction conditions were employed. From the 61 markers that gave a product, only eight showed a length polymorphism while 37 were monomorphic on the three divergent commercial turkey lines used. The remaining 16 markers yielded many unspecific bands and no specific amplification product could be obtained. Five polymorphic and eleven monomorphic products contained a detectable microsatellite repeat. Furthermore, of the markers that detected a polymorphism in turkey, the observed heterozygosity (15–50%) and allelic variation (only 2 in most cases) was very low. Therefore, on the basis of our results, we think that chicken microsatellite markers are not very useful for mapping purposes in turkey.     

Can the spread of agriculture in Europe be followed by tracing the spread of the weed Silene latifolia. A RAPD study

On the basis of gene frequency data of three flavone glycosylating genes, populations of the agricultural weed Silene latifolia (Caryophyllaceae) in Europe can be divided into two chemical races: an eastern and a western race. Morphological data also show a clear east-west division. When the two datasets are combined at least nine different geographical races can be distinguished using cluster analysis. Because these observations are hard to explain by selection, it has been proposed that these different races probably originated as a consequence of migration during the spread of agriculture over Europe in the past. To discriminate between selection and genetic drift many more selectively neutral easy-to-score characters are needed. In order to test whether random amplified polymorphic DNAs (RAPDs) might be suitable for this purpose, we performed a small-scale RAPD analysis on 16 geographical different populations. Using Jaccard's coefficient of similarity, we calculated genetic distances by pair-wise comparisons of both unique and shared amplification products, and a dendrogram was subsequently constructed using an unweighted pair-group method with arithmetical averages (UPGMA). On the basis of the dendrogram two clusters were discerned that clearly coincide with the aforementioned east-west division in populations. As there has been little or no artificial selection on this weed, its migration routes may be a good reflection of the different geographical routes agriculture has taken. We propose that a phylogenetic analysis of RAPD data of many more populations may provide additional information on the spread of agriculture over Europe.     

Isolation and identification of a non-specific tandemly repeated DNA sequence in Oryza species

A tandemly repeated DNA sequence (RRS7) was isolated from Oryza alta (CCDD). RRS7-related sequences were also found tandemly arrayed in genomes AA, BB, BBCC, CC, and EE, and a small amount of RRS7-related sequences were detected in genome FF and the Oryza species with unknown genomes. DNA sequence analysis of the 1844-bp insert of RRS7 revealed that it contained six tandemly repeated units, of which five were 155 bp in length and one was 194 bp in length and contained an imperfect internal 39-bp duplication. Southern blot analysis showed that the boundary sequence contained in RRS7 is a single-copy sequence. A 155-bp consensus sequence derived from the six monomeric repeats contained no internal repeat and showed no significant homology to other currently known sequences. The results of Southern blot and sequence analysis revealed that there are at least two subfamilies present in the RRS7 family; these are represented by the DraI site and the MspI site, respectively. Restriction digestion with two pairs of isoschizomers MboI/Sau3A and MspI/HpaII demonstrated that most of the C residues in the GATC sites and the internal C in the CCGG sites of the RRS7 family in O. Alta were methylated. The usefulness of the RRS7 family in determining the evolutionary relationship of the genome DD and other Oryza genomes is discussed.