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Biochemical Genetics (v.35, #11-12)
Temporal Variation of Allozyme Frequencies in Aedes albifasciatus (Diptera: Culicidae) from Argentina by Gladys B. de Sousa; Adolfo Jiménez; Antonio Blanco; Cristina N. Gardenal (pp. 339-349).
Aedes albifasciatus is a floodwater mosquito widely distributed in Argentina. It is important from economic and medical points of view. A 4-year survey of seasonal variation in allele frequencies in a population of this species was undertaken to determine possible changes in the genetic structure and their correlation with environmental conditions. Significant temporal variation was detected at most of the loci, but it did not follow a cyclic or seasonal pattern. Multivariate analysis of principal components showed a remarkable homogeneity of samples collected from December 1993 to April 1995 and a clear differentiation of the November 1991, March 1992, and November 1993 samples. This variation could be correlated with the magnitude of rainfall occurring in the area. Passive transport of larvae by water streams and river freshets produced by floods would have mixed larvae from breeding sites with different allele frequencies, causing the genetic differentiation observed.
Keywords: Aedes albifasciatus ; allozymic temporal variation; genetic distance; genetic structure; Argentina
Genetic Specificity of Stress-Induced Anemia in Rats by M. C. Datta; H. G. AbdelRahman; K. K. Srivastava; G. S. Smith (pp. 351-361).
There is a genetic difference in rat hemoglobin (Hb) β-chain structure, with alternate alleles, A and B, at a single locus. This study was designed to find out whether marrow sensitivity due to γ exposure and experimentally induced anemia in age-matched adult rats is entirely strain specific or is a combination of both strain and Hb genotype. Eight strains of inbred and outbred rats comprising AA and BB types were examined. The data indicate that there is a relationship between marrow sensitivity and Hb genotypes in response to erythropoietic stress caused by three techniques.
Keywords: rat; inbred and outbred strains; anemic stress; hemoglobin; genetic specificity
Comparison of mtDNA Variants Among Mediterranean and New World Introductions of the Mediterranean Fruit Fly Ceratitis capitata (Wied.) by Anna Kourti (pp. 363-370).
Restriction enzyme cleavage sites of mitochondrial DNA (mtDNA) from the Mediterranean fruit fly (Ceratitis capitata) were found to vary among Mediterranean and New World populations. A restriction map for six populations (one from Greece and five from the New World) is constructed for the Mediterranean fruit fly. Six diagnostic restriction enzymes (EcoRI, EcoRV, HaeIII, HindIII, SstI, XbaI) are assigned three geographically distinct main types, CI, CII, and CIII.
Keywords: Ceratitis capitata ; mitochondrial DNA; restriction maps; restriction fragment length polymorphism; population genetics
Genetic Variation in Some Populations of the Golden-Striped Salamander, Chioglossa lusitanica (Amphibia: Urodela), in Portugal by João Alexandrino; Nuno Ferrand; J. W. Arntzen (pp. 371-381).
Genetic variation in the golden-striped salamander (Chioglossa lusitanica) was assessed in 231 individuals from four Portuguese populations by means of horizontal starch gel electrophoresis and isoelectric focusing. Three of 19 enzyme systems, representing 21 presumptive loci, were found to be polymorphic: phosphoglucomutase 1 (PGM1), peptidase B (PEPB), and peptidase D (PEPD). The observed average heterozygosity in Chioglossa lusitanica (0.027) is significantly lower than that observed for other amphibians, either urodeles or salamandrids. Differences in allele frequencies and the presence of private alleles are indicative of a high degree of population differentiation. PEPD, in particular, seems to be a diagnostic locus separating the southernmost population studied from the others.
Keywords: Amphibia; polymorphism; golden-striped salamander; Chioglossa lusitanica ; Urodela; starch gel electrophoresis; isoelectric focusing
Allozyme Polymorphism and Geographic Variation in the Small Brown Planthopper, Laodelphax striatellus (Homoptera: Delphacidae) by Sugihiko Hoshizaki (pp. 383-393).
The small brown planthopper, Laodelphax striatellus, immigrates annually into Japan over the East China Sea from the Asian mainland. It is not known whether this long-distance dispersal has any effect on the genetic structure of Japanese L. striatellus populations. The dispersal of L. striatellus is suspected to be relevant to the population dynamics of infection with the parasitic bacterium Wolbachia, which causes cytoplasmic incompatibility in L. striatellus. Wolbachia infection has spread within and among Japanese L. striatellus populations due to this cytoplasmic incompatibility. In the present study, the geographic differences among 11 L. striatellus populations from Japan and Taiwan was investigated using allozyme polymorphism. FST values on three enzyme loci (GPI, PGM, and AK) indicated a geographically differentiated population structure. Significant differentiation was found even among populations located along the course of the long-distance dispersal. The results indicated that long-range dispersal of L. striatellus does not occur regularly over the main islands of Japan and that it does not have a large effect on the population structure of L. striatellus. This conclusion is in agreement with the geographically variable life history of L. striatellus adapted to local climates. The short-term rice stripe epidemic, which is vectored by L. striatellus, in northwestern Kyushu, Japan, during 1985 and 1986 corresponds to these results. Based on the present findings, short-distance dispersal was considered to drive the spatial spread of Wolbachia infection among L. striatellus populations.
Keywords: Laodelphax striatellus ; allozyme; geographic variation; dispersal; Wolbachia
Sequences of Exon 6 and the Adjacent Intron Boundaries of the Rat Platelet-Derived Growth Factor A-Chain Gene: Implications for Alternative Splicing by Wen-Yang Hu; Tomohiro Nakayama; Noboru Fukuda; Hirobumi Kishioka; Masayoshi Soma; Yoichi Izumi; Katsuo Kanmatsuse (pp. 395-405).
Platelet-derived growth factor (PDGF) is a potent stimulator of vascular smooth muscle cell growth. Two isoforms of PDGF A-chain mRNA that either include (long form) or exclude (short form) exon 6 are produced as a result of alternative splicing in mouse, rabbit, and human. The short form of PDGF A-chain is expressed in both resting and activated cells, while the long form is present predominantly in activated cells. Reverse transcription-polymerase chain reaction analysis with primers encompassing exon 6 revealed the presence of both long- and short-form PDGF A-chain transcripts in rat vascular smooth muscle cells. The nucleotide sequences of exon 6 and its intron boundaries were determined from rat vascular smooth muscle cell cDNA and rat leukocyte genomic DNA. Translation of the long form of PDGF A-chain mRNA was shown to terminate in the 70-base pair exon 6. Conserved sequences that may contribute to the regulation of alternative RNA splicing were identified in intron 5.
Keywords: platelet-derived growth factor; polymerase chain reaction; polypyrimidine; alternative splicing; rat; vascular smooth muscle