Sperm utilization and post-copulatory female-guarding in the Colorado potato beetle, Leptinotarsa decemlineata

Crosses between white and black color morphs of the Colorado potato beetle, Leptinotarsa decemlineata Say, used as genetic markers, showed that male beetles ride and guard females to achieve the three copulations required to fill the spermatheca. Multiple matings are necessary for the females to realize their full reproductive potential. Sperm mixing occurs in the spermatheca providing partial sperm precedence. The data support the competitive mate searching theory.

---

Résumé Différentes combinaisons d'accouplements entre des mutants noirs et blancs du doryphore de la pomme de terre, Leptinotarsa decemlineata, servirent à étudier le comportement de guarde de la femelle par le mâle après un premier accouplement. Les résultats indiquent que le sperme de deux mâles accouplant la même femelle se mélange dans la spermathèque assurant ainsi un certain niveau de précédence du sperme du dernier mâle.La masse de sperme dans la spermathèque était inférieure à sa capacité chez les femelles ayant été accouplées une ou deux fois. Le doryphore mâle aurait donc avantage à demeurer sur la femelle après un premier accouplement afin d'obtenir le minimum de trois accouplements requis pour remplir la spermathèque avant que les autres mâles puissent accoupler cette femelle. Les autres mâles ont avantage à essayer de dérober cette femelle pour remplir eux mêmes la spermathèque ou tout au moins profiter d'une certaine précédence du sperme du dernier mâle pour fertiliser une partie des oeufs.Sans accouplements multiples, la femelle ne possède pas suffisamment de sperme pour féconder tous ses oeufs. II semble aussi que les accouplements répétés puissent augmenter sa fécondité.Les résultats supportent une stratégie reproductive de compétition plutôt qu'une simple maximisation du nombre d'accouplements.

     

Redistribution of Lyt-bearing T cells in acute murine experimental allergic encephalomyelitis: selective migration of Lyt-1 cells to the central nervous system is associated with a transient depletion of Lyt-1 cells in peripheral blood

Experimental allergic encephalomyelitis (EAE) was induced in SJL/J mice by using two injections of spinal cord homogenate in incomplete Freund's adjuvant supplemented with mycobacteria. Analysis of circulating Lyt-bearing subsets by indirect immunofluorescence during the course of acute EAE revealed the following: 1) during the pre-clinical phase of EAE (1 to 2 days before the onset of paralysis), there was a decrease in the percentage of Lyt-1- but not of Lyt-2-bearing cells in peripheral blood, and of both Lyt-1- and Lyt-2-bearing cells in spleen; 2) with the onset of clinically evident EAE, there was a decrease in both Lyt-1 and Lyt-2 cells in peripheral blood and an increase in the percentage of Lyt-1-bearing cells in pooled inguinal and axillary lymph node; and 3) after these early changes, there was a rapid reconstitution of the percentages of total Lyt-bearing cells and of both Lyt-1- and Lyt-2-bearing cells in peripheral blood. Immunohistochemical analysis of the central nervous system infiltrate revealed that the earliest lesions consisted predominantly of Lyt-1 T lymphocytes, with few Lyt-2 cells present. These results demonstrate that the influx of cells of the Lyt-1 inducer subset to the central nervous system in acute EAE is accompanied by a transient decrease in Lyt-1 cells in peripheral blood.     

CCK nerve terminals in the rat striatal and limbic areas originate partly in the brain stem and partly in telencephalic structures

After direct injection of colchicine into the rat rostral caudateputamen, levels of cholecystokinin-like immunoreactive (CCK-IR) material in this part of the nucleus are significantly lowered, and CCK-IR neuronal cell bodies are not demonstrable in the caudateputamen, although numerous ones are revealed in some adjacent telencephalic regions. Direct injection of kainic acid into the rostral caudate-putamen is not followed by a decrease of CCK-IR material in the lesioned region. Twenty one days after injection of 6-hydroxydopamine into the rat ventral mesencephalon, a significant decrease of CCK-IR material is observed in the frontal pole, the pyriform cortex, the nucleus accumbens and the ventral mesencephalon itself, but not in the caudate-putamen. After brain stem hemitransection, no decrease in CCK-IR material is observed in the rostral caudate-putamen.     

Nuclear activity during oogenesis in sea urchins

Summary Early meiotic stages of Arbacia punctulata oocytes have revealed the presence of synaptinemal complexes in the chromosomes, which persist through zygotene-pachytene. The synaptinemal complexes conform broadly to the usual tripartite structures found in other higher forms. In addition, nuclei at these stages consist of a small nucleolus and dense bodies of varying sizes. The nucleolus is fibrillar in texture throughout and does not seem to incorporate Uridine-5-³H after pulse labeling, whereas the chromosomes are labeled. The nucleolar label is visualized at diplotene stages and onwards. The nuclear envelope differentiates by the appearance of numerous nuclear pore complexes with dense material in the annuli, and the chromosomes become markedly diffused. At vitellogenesis stage the nucleolus and chromatin become highly labeled after pulse incorporation of Uridine, indicating synthesis of ribosomal and chromosomal RNAs.This investigation was supported by grants No. A-5049, A-3624 and D-17 from National Research Council, Canada, grant No. DRB-9340-05 (U6) from Defense Research Board, Canada, and grant No. DRG-918 AT from Damon Runyon Memorial Fund for Cancer Research.     

Arginine utilization by Chlorella autotrophica and Chlorella saccharophila

Chlorella saccharophila can utilize the amino acids arginine, glutamate. ornithine and proline as sole sources of nitrogen for growth. By comparison C. autotrophica utilized only arginine and ornithine. Following osmotic shock of Chlorella autotrophica from 50 to 150% artificial seawater rapid synthesis of proline (the main osmoregulatory solute in this alga) occurred in cells grown on arginine or citrulline. However, little proline synthesis occurred in ornithine-grown cells. Distribution of radiolabelled carbon from [¹⁴C]-arginine assimilation following osmotic shock of C. autotrophica agrees with the following pathway of arginine utilization: arginine→citrulline→ornithine→glutamate semialdehyde→pyrroline-5-carboxylate→proline. These 4 steps are catalysed by arginine deiminase (EC 3.5.3.6), citrullinase (EC 3.5.1.20), ornithine transaminase (EC 2.6.1.13) and pyrroline-5-carboxylate reductase (EC 1.5.1.2), respectively. Of these 4 enzymes, only arginine deiminase and pyrroline-5-carboxylate reductase were detected in the crude extract of the 2 Chlorella species. Arginine deiminase did not require specific cations for optimal activity. The deimi-nase showed maximal activity at pH 8.0 and followed Michaelis-Menten kinetics with an apparent K_m for L-arginine of 0.085 m M for the C. autotrophica enzyme and 0.097 m M for that of C. saccharophila. The activity of arginine deiminase was not influen-ced by growing C. saccharophila on arginine. Ornithine competitively inhibited arginine deiminase with an apparent K, of 2.4 m M for the C. autotrophica enzyme, and 3.8 m M for that of C. saccharophila . Arginine utilization by Chlorella is discussed in relation to that of other organisms.     

Zinc, a novel structural element found in the family of bacterial adenylate kinases.

The adk gene from Bacillus stearothermophilus was cloned and overexpressed in Escherichia coli under the control of the lac promoter. The primary structure of B. stearothermophilus adenylate kinase exhibited 76% identity with the enzyme from Bacillus subtilis, 60% identity with the enzyme from Lactococcus lactis, and 42% identity with the enzyme from E. coli. The most striking property of the adenylate kinase from B. stearothermophilus is the presence of a structural zinc atom bound to four cysteines in a zinc finger-like fashion. The ability to coordinate zinc is predicted also for a number of other isoforms of bacterial adenylate kinases. Furthermore, the tightly bound metal ion contributes to the high thermodynamic stability of adenylate kinase from B. stearothermophilus.     

Allelic polymorphism in the hamster oviductin gene is due to a variable number of mucin-like tandem repeats

Oviductins are high-molecular-weight glycoproteins specifically secreted by the oviduct. These proteins bind to the zona pellucida of the ovulated oocyte and remain associated with the embryo during its transit in the oviduct. They may be involved in fertilization and early embryonic development. In order to explore their putative biological function, the cDNA sequence corresponding to oviductin in the golden hamster was determined. We found that the deduced amino acid sequence of this heavily O-glycosylated protein presents characteristics typical of mucins, including serine- or threonine-rich tandem repeats. Analysis of several cDNA clones and of genomic DNA revealed the presence of a single copy gene with two frequent alleles differing in the number of repeats. Comparison with oviductin sequences from other mammals indicates a high degree of conservation amongst species, except for the repeat region which shows divergence, notably in the number of repeats. Based on its biochemical and genetic properties, hamster oviductin can now be classified as a secretory mucin. This concept provides a new insight in the elucidation of its biological role: oviductin could possibly provide the oviduct and the oocyte with a protective coating ensuring normal tubal function and embryonic development. © 1995 wiley-Liss, Inc.     

Effects of T3 and rearing temperature on growth and skeletal myosin heavy chain isoform transition during early development in the salmonid Salvelinus alpinus (L.)

Rearing of 1-year-old Arctic charr (Salvelinus alpinus) at 12°C, as well as the administration of 50 or 75 mgT₃/kg feed, accelerated the neonatal to adult fast myosin heavy chain transition, but the effect of temperature was more dramatic than the effect of T₃ administration. The endogenous plasma levels of T₃ in charrs reared at 12°C were higher than those of analogous groups reared at natural temperature, which in the period under study was between 0.5 and 12°C. As in other species, T₃ seemed to play a role in the regulation of the neonatal to adult fast myosin isoform transition by down-regulating the levels of the neonatal and increasing the levels of an adult fast myosin heavy chain. Temperature seemed to accelerate this transition at least, but not only, by inducing an increase in the endogenous levels of T₃ in the Arctic charr.