Radioiodination and characterization of the plasma membrane of sea urchin sperm

Two methods were used to radioiodinate sea urchin sperm: lactoperoxidase-glucose oxidase and Iodo-Gen. Following iodination the sperm are viable, they undergo the acrosome reaction, and they fertilize eggs. Of the radioactivity associated with the labeled sperm, 28–50% is presumed to be free ¹²⁵I^?, 37–47% is incorporated in lipid, and 8–15% is in trypsin-digestible material believed to be protein. Digestion of the labeled, living sperm with trypsin removes 95.6–99.5% of the macromolecular label (the cells are alive after digestion) suggesting that almost all the protein label is on the external surface of the cell. Thin-layer chromatography of the lipid fraction shows that the major membrane phospholipids and cholesterol are labeled. SDS-PAGE analysis shows the protein-incorporated ¹²⁵I is distributed among four glycoproteins of >250K, 84K, 64K, and 52K dalton apparent molecular weight. Twenty-eight percent of the total protein (trypsin-digestible) label is in the 84K component and 46% in the 64K band. Although both molecules contain much of the label, they are relatively minor components of the TX-100 extract of sperm. The methods outlined will be useful in determining the role of sperm surface components in fertilization.     

Intrinsic vs. extrinsic influences on life history expression: metabolism and parentally induced temperature influences on embryo development rate

Intrinsic processes are assumed to underlie life history expression and trade‐offs, but extrinsic inputs are theorised to shift trait expression and mask trade‐offs within species. Here, we explore application of this theory across species. We do this based on parentally induced embryo temperature as an extrinsic input, and mass‐specific embryo metabolism as an intrinsic process, underlying embryonic development rate. We found that embryonic metabolism followed intrinsic allometry rules among 49 songbird species from temperate and tropical sites. Extrinsic inputs via parentally induced temperatures explained the majority of variation in development rates and masked a relationship with metabolism; metabolism explained a minor proportion of the variation in development rates among species, and only after accounting for temperature effects. We discuss evidence that temperature further obscures the expected interspecific trade‐off between development rate and offspring quality. These results demonstrate the importance of considering extrinsic inputs to trait expression and trade‐offs across species.     

Frost resistance of winter rape leaves as related to the changes in water potential and growth capability

Differential thermal analysis indicated that the frost resistance of winter rape leaves ( Brassica napus L. var. oleifera L. cv. Gòrczanski), collected from plants grown in the cold (5/2°C), relies mainly on their ability to supercool to −9 to −11°C, i.e. consists in freezing avoidance. Initiation of ice formation in the cold-acclimated leaves resulted in the death of more than 50% of the cells as determined with a conductivity method. The development of freezing tolerance appeared to be an attribute of the second stage of plant hardening and was induced by the exposure of plants to a slightly subzero temperature (−5°C) for 18 h. Such a treatment brought about a sudden and persistent water potential decrease in the leaves, despite the fact that they had reabsorbed water from the medium prior to water potential measurements. Water potential changes were associated with a higher growth capability of the leaves as checked by determinations of disk area increments. It is suggested that the increased frost tolerance of the cold-grown winter rape leaves, subjected to subfreezing temperature, is related to the decreased water potential of the tissue caused by changes in turgor and/or in osmotic pressures of the cells.     

Induction of interleukin-2 receptor by tumor necrosis factor α on cultured ovarian tumor-associated lymphocytes

Summary We have recently reported that autologous tumor-specific cytotoxic T lymphocyte (CTL) lines and clones can be developed from lymphocytes infiltrating ovarian malignant ascites (TAL). In this study, we investigated the biological effects of tumor necrosis factor (TNF) in the induction, expansion, long-term proliferation and lytic function of CD8⁺ TAL. TNF up-regulated the IL-2 receptor (IL-2R) chain (Tac antigen) on the surface of CD3⁺ CD8⁺ CD4^– TAL, enhanced the proliferation of autologous tumor-specific CTL, and potentiated their lytic function in long-term cultures. Furthermore, in the induction and expansion phase of CD8⁺ TAL, the presence of TNF was associated with a selective increase in CD8⁺ IL-2R⁺ (Tac⁺) cells, and subsequent decrease in CD4⁺ IL-2R⁺ (Tac⁺) cells. These results suggest that the observed facilitation of the outgrowth of CD8⁺ cells in TAL cultures may be due, at least in part, to the up-regulation of IL-2R, and indicate the usefulness of TNF in the analysis of signalling in autologous tumor-reactive CTL.     

Effects of cold on CO2 exchange in winter rape leaves

A viable wheat hybrid intermediate of the same height as the parents was obtained by crossing the female parent of tall variety NP4 with the male parent of the dwarf variety HD2160. Seeds of the hybrid and its parents were germinated and their growth pattern as well as the activities of peroxidase, indolyl-3-acetic acid oxidase and amylase in extracts made from them were studied at the early seedling stages i.e. up to 96 h.
A positive correlation existed between the length of the axis at the early seedling stage and at mature plant height as far as the parental varieties are concerned but no such correlation was observed with the hybrid. Growth of the hybrid seedlings was less than of its parents. Light appeared to stimulate the longitudinal growth of the axis to different extents in the parents and hybrid. Higher activities of peroxidase, indolyl-3-acetic acid oxidase and amylase were observed in the hybrid as compared to both of its parents. Lethal wheat hybrid also exhibits increased activities of amylase, indolyl-3-acetic acid oxidase and peroxidase. Therefore, it appears that seedling growth and enzyme activities at the seedling stage are not always correlated with hybrid vigour.     

Efficient degradationin vitro of all intermediate filament subunit proteins by the Ca2+-activated neutral thiol proteinase from Ehrlich ascites tumor cells and porcine kidney

Vimentin, desmin, glial fibrillary acidic protein, neurofilament triplet proteins, and a mixture of cytokeratins were digested with Ca²⁺-activated neutral thiol proteinase isolated from Ehrlich ascites tumor (EAT) cells and porcine kidney. All intermediate filament proteins were degraded by the proteinase, although with different rates and Ca²⁺ optima. These results are in part at variance with our previous statement that the Ca²⁺-activated proteinase from EAT cells is specific for vimentin and desmin.     

The key role of residue 5 in angiotensin II

The conformation–biological activity relationships in a series of angiotensin II analogs substituted in position 5 were studied. Results indicated that only analogs with β-branched residue in position 5 possess spectral and biological properties identical to that of parent angiotensin II.