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Biochemical Genetics (v.39, #1-2)

Genetic Studies of Psammolestes tertius (Hemiptera: Reduviidae: Triatominae) Using Male Genital Morphology, Morphometry, Isoenzymes, and Random Amplified Polymorphic DNA by R. P. P. Soares; S. E. Barbosa; E. C. Borges; T. A. Melo Júnior; A. J. Romanha; J. P. Dujardin; C. J. Schofield; L. Diotaiuti (pp. 1-13).

Two Brazilian populations of Psammolestes tertius (Ceará and Minas Gerais) collected from thornbird nests (Furnariidae) were compared by male genital morphology, morphometry, isoenzymes, and random amplified polymorphic DNA (RAPD). Male genitalia showed no difference between the populations. In contrast, morphometry, isoenzyme, and RAPD clearly distinguished the two populations. Possible mechanisms of dispersal and the origin of Psammolestes are discussed.

Keywords: Psammolestes tertius; isoenzymes; random amplified polymorphic DNA; morphometry; male genital morphology

Complementation Cloning and Characterization of the Pyrroline 5-Carboxylate Reductase Gene from Drosophila melanogaster by S. R. Misener; V. K. Walker (pp. 15-31).

The first insect cDNA and genomic sequences encoding pyrroline 5-carboxylate reductase (EC 1.5.1.2) have been isolated from Drosophila melanogaster. The cDNA sequence was identified by interspecies complementation of an E. coli proline auxotroph and encodes a protein 280 amino acids in length with 25–41% identity to pyrroline 5-carboxylate reductases isolated from other organisms. The corresponding gene is single copy and is located at cytological position 91E-F, and in one of the P1 clones in that region. With a single 61-bp intron, and an impressively small 135- to 200-bp region that presumably acts as a bidirectional promoter, the gene itself shows remarkable economy. The calculated molecular weight of 29,700 predicts that the native enzyme is likely an octomer. Sequencing of the promoter region and expression studies, as well as the known function of the enzyme in redox regulation and the high levels of free proline in insects, suggest that this housekeeping gene encodes an enzyme with a crucial role in intermediary metabolism.

Keywords: pyrroline 5-carboxylate reductase; proC complementation; Drosophila genome; proline biosynthesis

cDNA of a Novel mRNA Expressed Predominantly in Mouse Kidney by Takeshi Kawamura; Noriyuki Kuroda; Yuko Kimura; Eliada Lazoura; Noriko Okada; Hidechika Okada (pp. 33-42).

We examined embryonic carcinoma (EC) cells for a potential prototype molecule of C3, the third component of complement. PCR primers, corresponding to the base sequence derived from the C3 cDNA of several species, were used for PCR amplification of the EC cell cDNA. All the PCR products obtained had the same sequence and showed no sequence homology to C3. Subsequently, cDNA clones were isolated from a mouse liver cDNA library using the PCR product as a probe. Unexpectedly, neither the base sequence of the cDNA clones nor the amino acid sequence deduced from the cDNA showed homology to C3, although partial homology was observed to a number of sequences from EST databases. We designated this new clone NCU-G1. Northern hybridization experiments revealed that NCU-G1 is expressed constitutively not only in the mouse fetus but also in various mouse tissues, and is most abundant in the kidney cortex.

Keywords: embryonic carcinoma cells; mRNA; mouse kidney; C3; pregnancy

Genetic Variation in Indian Populations of Scirpophaga incertulas as Revealed by RAPD-PCR Analysis by Lalitha Sunil Kumar; Arun S. Sawant; Vidya S. Gupta; Prabhakar K. Ranjekar (pp. 43-57).

Scirpophaga incertulas, commonly referred to as yellow stem borer, is a predominant pest of rice causing serious losses in its yield. Genetic variation among populations of Scirpophaga incertulas collected from 28 hotspot locations in India was examined using the randomly amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR). In all, 32 primers were used and 354 amplification products were observed. No RAPD-PCR bands diagnostic to the pest population from any specific region were identified. Cluster analysis using UPGMA showed that, with the exception of the pest population from Pattambi, all the populations cluster as one group with GD values in the range of 6–22%, suggesting that gene flow between populations is independent of geographic distance and appears to be unrestricted. The relatively high GD value of 48% exhibited by the pest population from Pattambi was the only exception.

Keywords: Scirpophaga incertulas; RAPD-PCR; genetic variation; gene flow

Characterization of Baboon (Papio hamadryas) Milk Proteins by A. J. Hall; A. Masel; K. Bell; J. A. Halliday; D. C. Shaw; J. L. VandeBerg (pp. 59-71).

The major proteins of baboon milk were identified as β-lactoglobulin (βLG), α-lactalbumin (αLA), lysozyme, lactoferrin, casein, and albumin by immobiline isoelectric focusing, SDS-PAGE, immunoblotting of gels with rabbit antisera to human αLA, lysozyme, and albumin and bovine βLG and casein, and N-terminal sequencing of proteins blotted from gels. The first 30 N-terminal residues of baboon βLG are identical to those of macaque (Macaca fasicularis) βLG except for a (D/N) polymorphism at residue 2. The complete cDNA sequence and derived amino acid composition of βLG were elucidated using RT-PCR amplification of poly(A)⁺ mRNA purified from lactating mammary gland. Baboon βLG consists of 168 amino acid residues (M_r 20,750) and is the longest βLG identified to date. βLG and αLA polymorphisms with three (A, B, and C) and two (A and B) variants, respectively, were detected by immobiline IEF, pH 4–6, of individual baboon milk samples at varying stages of lactation.

Keywords: baboon; milk; β-lactoglobulin; polymorphism; cDNA

Reduced Enzyme Activity Following Hsp70 Overexpression in Drosophila melanogaster by Robert A. Krebs; Sari H. Holbrook (pp. 73-82).

Acclimation to environmental change can impose costs to organisms. One potential cost is the change in cell metabolism that follows a physiological response, e.g., high expression of heat shock proteins may alter specific activity of important enzymes. We examined the significance of this cost in a pair of Drosophila melanogaster lines transformed with additional copies of a gene that encodes the heat shock protein, Hsp70. Heat shock induces Hsp70 expression in all lines, but lines with extra copies produce much more Hsp70 than do excision control strains. The consequence of this supranormal Hsp70 expression is to reduce specific activity of both enzymes analyzed, adult alcohol dehydrogenase (ADH), which is heat sensitive, and lactate dehydrogenase, which is not. Strain differences were most pronounced under those conditions where Hsp70 expression was maximized, and not where the heat stress denatured proteins. That result supported the idea that Hsp70 expression is constrained evolutionarily by its tendency to bind nascent peptides when overabundant within the cell.

Keywords: enzyme activity; Hsp70; Drosophila melanogaster; heat shock; metabolism; stress; trade-offs

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Biochemical Genetics (v.39, #1-2)

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Biochemical Genetics (v.39, #1-2)