Sexual dimorphism in the pyrgomorphid grasshopper Phymateus morbillosus: from wing morphometry and flight behaviour to flight physiology and endocrinology

Abstract In the field, adult males of the grasshopper Phymateus morbillosus are able to fly for up to 1 min and cover up to c. 100 m, whereas females, although fully winged, are apparently unable to get airborne. Morphometric data indicate that the males are lighter, have longer wings, a higher ratio of flight muscles to body mass, and a lower wing load value than females. It was investigated whether this inability of females to fly is related to fuel storage, flight muscle enzymatic design and/or the presence and quantitative capacity of the endocrine system to mobilize fuels. In both sexes, readily available potential energy substrates are present in the haemolymph in similar concentrations, and the amount of glycogen in flight muscles and fat bodies does not differ significantly between males and females. Mass-specific activities of the enzymes GAPDH (glycolysis), HOAD (fatty acid oxidation) and MDH (citric acid cycle) in flight muscles are significantly lower in females compared with males, and mitochondria are less abundant in the flight muscles of females. There is no significant difference between the ability of the two sexes to oxidize various important substrates. Both sexes contain three adipokinetic peptides in their corpora cardiaca; the amount of each peptide in female grasshoppers is higher than in males.
Thus, despite some differences listed above, both sexes appear to have sufficient substrates and the necessary endocrine complement to engage in flight. It seems more likely, from the morphometric data above, that the chief reason for flightlessness is that P. morbillosus females cannot produce sufficient lift for flight; alternatively, the neuronal functioning associated with the flight muscles may be impaired in females.     

A familial mutation in the testis-determining gene SRY shared by both sexes

A familial mutation in SRY, the gene coding for the testis-determining factor TDF, was identified in an XY female with gonadal dysgenesis, her father, her two brothers and her uncle. The mutation consists of a T to C transition in the region of the SRY gene coding for a protein motif known as the high mobility group (HMG) box, a protein domain known to confer DNA-binding specificity on the SRY protein. This point mutation results in the substitution, at amino acid position 109, of a serine residue for phenylalanine, a conserved aromatic residue in almost all HMG box motifs known. This F109S mutation was not found in 176 male controls. When recombinant wildtype SRY and SRY^F109S mutant protein were tested in vitro for binding to the target site AAC AAAG, no differences in DNA-binding activity were observed. These results imply that the F109S mutation either is a rare neutral sequence variant, or produces an SRY protein with slightly altered in vivo activity, the resulting sex phenotype depending on the genetic back-ground or environmental factors.This paper is dedicated by G. S. to Professor Ulrich Wolf on the occasion of his 60th birthday     

Asymmetric segregation of heat-shock proteins upon cell division in Caulobacter crescentus

Three Caulobacter crescentus heat-shock proteins were shown to be immunologically related to the Escherichia coli heat-shock proteins GroEL, Lon and DnaK. A fourth heat-shock protein was detected with antibody to the C. crescentus RNA polymerase. This 37,000 Mr heat-shock protein might be related to the E. coli 32,000 Mr heat-shock sigma subunit. The synthesis of the major C. crescentus RNA polymerase sigma factor was not induced by heat shock. The E. coli GroEL protein and the related protein from C. crescentus were also induced by treatment with hydrogen peroxide. Like some of the proteins in the heat-shock protein families of Drosophila and yeast, the four heat-shock proteins in C. crescentus were found to be regulated developmentally under normal conditions. All four proteins were synthesized in the predivisional cell, but the progeny showed cell type-specific bias in the level of enhanced synthesis after heat shock. The 92,000 Mr Lon homolog and the 37,000 Mr RNA polymerase subunit were preferentially synthesized in the stalked cell, whereas the synthesis of the 62,000 Mr GroEL homolog was enhanced in the progeny swarmer cell. Furthermore, the four heat-shock proteins synthesized in the predivisional cell were partitioned in a specific manner upon cell division. The stalked cell, which initiates chromosome replication immediately upon division, received the Lon homolog, the DnaK homolog and the 37,000 Mr RNA polymerase subunit. The GroEL homolog, however, was distributed equally to both the stalked cell and the swarmer cell. These results provide access to the functions of C. crescentus heat-shock proteins under both normal and stress conditions. They also allow an investigation of the regulatory signals that modulate the asymmetric distribution of proteins and their subsequent cell type-specific expression in the initial stages of a developmental program.     

A detailed study of the periodate oxidation of sialic acids in glycoproteins

Periodate oxidation of terminalN-acetyl- andN-glycoloylneuraminic acid residues in the mucins from edible bird nest substance and pig submandibular gland, respectively, can be carried out under conditions which exclusively give rise to the formation of the C-7 analogues of these sialic acids. In contrast, the C-8 compounds can be obtained in a maximum yield of about 40%. Under identical conditions,N-glycoloylneuraminic acid is oxidized about 1.5 times faster than theN-acetylated derivative. After release of the sialic acids by acid hydrolysis, the characterization of the oxidation products was carried out by TLC, by GLC and GLC-MS of the corresponding pertrimethylsilyl derivatives, and by 500-MHz¹H-NMR spectroscopy. In addition, molar response factors for GLC analysis and extinction coefficients in the orcinol/Fe³⁺/HCl assay were determined.     

Uptake and utilization of lipids by Paramecium tetraurelia

Uptake rates of a variety of 14C-labeled fatty acids and complex lipids by Paramecium tetraurelia during 48 h of log-phase growth varied. Fatty acid uptake was maximal during lag phase of growth when phagosome (food vacuole) formation was minimal. Food vacuole formation was shown to be suppressed by the presence of exogenous lipids and by starvation. The rates of uptake of lipids were significantly greater than those of small organic compounds such as amino acids, cyclitols, fatty acid precursors and metabolic intermediates. Significant amounts of radioactivity from 14C-labeled fatty acids were metabolized to 14CO2. The uptake rates of different saturated, straight-chain fatty acids of even carbon numbers were different and were not correlated with chain length, results suggesting that the primary mechanism for uptake of these compounds was neither by bulk transport nor simple diffusion and that carrier-mediated processes could possibly be involved.     

Characterisation of neuropeptides of the AKH/RPCH-family from corpora cardiaca of Coleoptera

Summary Extracts of corpora cardiaca from two members of the family Tenebrionidae,Zophobas rugipes andTenebrio molitor, from one member of the Chrysomelidae,Leptinotarsa decemlineata, and from three members of the Scarabaeidae,Pachnoda marginata, P. sinuata andMelolontha hippocastani, were assayed for adipokinetic and hypertrehalosaemic activity in acceptor locusts (Locusta migratoria) and cockroaches (Periplaneta americana), respectively. All corpus cardiacum material tested, except that from the cockchafer,M. hippocastani, gave positive bioassay results. Biological activities of corpus cardiacum extracts from all species investigated can be resolved on reversed-phase high performance liquid chromatography (RP-HPLC). Gland extracts from the two tenebrionid species each show a single peak of biological activity associated with a single peak of UV absorbance having an identical retention time in both species. The two biologically active fractions from the corpora cardiaca of the potato beetle,L. decemlineata, coelute with exogenous (synthetic) hypertrehalosaemic hormones I and II of the American cockroach. The two species of the genusPachnoda contain two active compounds in their glands; compound I of each species is more abundant and elutes just ahead of the (synthetic) hypertrehalosaemic hormone of the cockroachBlaberus discoidalis. The gland material ofM. hippocastani exhibits and absorbance peak with the same retention time as the major peak from thePachnoda-species; however, this peak material does not elicit biological activity in the assays used here. After fractionation by RP-HPLC the main biologically active compounds were subjected to amino acid analyses. All factors are peptidic and contain 8 amino acid residues. The peptides from the tenebrionid species have the amino acid residues Asx₍₂₎, Glx₍₁₎, Ser₍₁₎, Pro₍₁₎, Leu₍₁₎, Phe₍₁₎ and Trp_(i), whereas the main peptide from corpora cardiaca ofP. marginata contains the residues Asx₍₂₎, Glx₍₁₎, Ser₍₁₎, Pro₍₁₎, Tyr₍₁₎, Leu₍₁₎ and Trp₍₁₎. Amino acid composition analyses of the two active fractions fromL. decemlineata reveal the residues Asx₍₂₎, Glx₍₁₎, Ser₍₁₎, Pro₍₁₎, Val₍₁₎, Phe₍₁₎ and Trp₍₁₎ for compound I and Asx₍₁₎, Glx₍₁₎, Thr₍₂₎, Pro₍₁₎, Leu₍₁₎, Phe₍₁₎ and Trp₍₁₎ for compound II.     

Inhibitory effect of nonviable preparations from human immunodeficiency virus 1 on inositol phospholipid metabolism

Previously it was established [Pahwa, S., Pahwa, R., Saxinger, C., Gallo, R. C. & Good, R. A. (1985) Proc. Natl. Acad. Sci. USA 82, 8198] that nonviable preparations of human immunodeficiency virus 1 (HIV-1) abolish the proliferative response of human lymphocytes to phytohemagglutinin A. Now we describe that this effect might be, at least partially, due to an impairment of the function of phospholipase C. It was found that addition of HIV-1 preparation to lymphocytes diminished the stimulation of phosphatidylinositol phosphorylation caused by phytohemagglutinin A. Moreover, this preparation completely abolished the phytohemagglutinin-A-stimulated release of inositol trisphosphate and prevented a translocation of protein kinase C from cytosol to membranes. From this data we conclude that nonviable HIV-1 preparations inhibit the intracellular signalling pathway, leading to a reduced mitogenic response to phytohemagglutinin A, at the level of protein kinase C.     

Association of Tat protein and viral mRNA with nuclear matrix from HIV-1-infected H9 cells

The transactivating protein from human immunodeficiency virus type 1 (HIV-1), Tat, was found to bind to the nuclear matrix from uninfected and HIV-1-infected H9 cells. Addition of the Zn2+, Cd2+ and Cu2+ chelator o-phenanthroline destroyed the matrix fibrils and the binding affinity of Tat to the matrix. A sequential treatment of the matrix, first with o-phenanthroline and then with ZnCl2, partially restored the fibrillar-like matrix structure. Infection of H9 cells with HIV-1 resulted in a displacement of cellular mRNA by viral mRNA from the nuclear matrix. Both the matrix-bound host cell and HIV-1 mRNA were found to dissociate from the matrix in the presence of o-phenanthroline. This could be prevented by coincubation with Zn2+ or Cu2+ (but not Mg2+), which stabilize the mRNA containing nuclear matrix structure.