Cytochalasin B blocks sperm incorporation but allows activation of the sea urchin egg

Cytochalasin B (CB) (2 × 10⁻⁶ M) prevents the incorporation of sperm into the eggs of Lytechinus pictus and Strongylocentrotus purpuratus as judged by light and transmission electron microscopy (TEM). At lower concentrations of CB (2 × 10⁻⁷ M), sperm are successfully incorporated into the egg, but their migration in the area of the egg cortex is impaired. The site of action of CB on the sperm may be on the initial rotation of the sperm nucleus in the cortex; the subsequent migration is not affected by CB. Although sperm incorporation is prevented at the higher CB concentrations, the eggs become activated—as judged by cortical reaction, increased protein synthesis and increased respiration. These findings raise the concept that egg activation by sperm could result from some pre-fusion event and hence that sperm-egg fusion would not be a prerequisite for the triggering of development. An alternative hypothesis is that fusion occurs between the acrosome process membrane and egg membrane, but since CB has destroyed the integrity of the cortex actin, the fusion bridge is so weak that it cannot be maintained without some contractile or cytoskeletal support by the cortex. The sperm may activate the CB-treated egg in the same manner as pricking with a microelectrode sometimes does.     

Evaluation of Bone Strength During Aflatoxicosis and Ochratoxicosis

Young chickens were fed graded levels of aflatoxin (0, 0.625, 1.25, 2.5, 5.0, and 10.0 μg/g of diet) or ochratoxin (0, 0.5, 1.0, 2.0, 4.0, and 8.0 μg/g of diet), and the breaking strength, displacement before failure, and diameter of their tibias were determined. Breaking strength was decreased at growth inhibitory levels of aflatoxin (2.5 μg/g) and ochratoxin (2 μg/g), whereas a reduction in diameter required higher levels (5.0 and 4.0 μg/g, respectively). Bones from birds with ochratoxicosis selected to have diameters equal to control bones had lower breaking strength. In an attempt to negate mathematically the effect of decreased diameter and bias in any selection process, stress at time of failure of the bones was calculated and found to be decreased by feeding aflatoxin but not ochratoxin. Total displacement of bones before breaking was increased significantly (P < 0.05) by both toxins at the highest levels administered, but this increase was primarily the result of an increase in displacement from the start of failure to complete failure. Increased displacement associated with both toxicoses was equal in bones selected to be of equal diameter or in bones from the same treatment but of different diameters. However, calculation of modulus of elasticity which is corrected for diameter revealed aflatoxin had no effect whereas ochratoxin tripled the effect. These data indicate that the material properties of bones can be altered during mycotoxicoses and suggest yet another way in which mycotoxins are detrimental to animal health.     

Fluorometric assay for 1-deoxyfructose

A sensitive fluorometric assay has been developed for the measurement of 1-deoxyfructose in biological fluids. Samples containing 1-deoxyfructose are incubated with an equal volume of 0.01 m 3,5-diaminobenzoic acid in 5.0 m phosphoric acid in a boiling-water bath for 15 min. The fluorescent product has an emission maximum at 502 nm and an excitation maximum at 396 nm. Fluorescence is proportional to 1-deoxyfructose concentrations over a range from 0.002 to 1.0 mm. The method can be used to detect as little as 0.03 μmol of 1-deoxyfructose in deproteinized blood and in urine and no interference is observed with glucose, fructose, pyruvate, or ketone bodies. The method will also detect 1-deoxytagatose, 2-deoxyaldohexoses, and -pentoses, 2,5-anhydromannose, and a number of 2-, 3-, 4-, and 5-mono- or bis(hydroxymethyl)furans. The fluorescence properties of the products formed from all of the above compounds are similar suggesting structural similarities of the adducts formed and possible mechanistic similarities of the reactions involved.     

Patterns of turning in courtship orientation of the male German cockroach

Courtship turning of the male German cockroach, Blattella germanica, was analysed with respect to rotational and translational movements. Three different sources of orientation information are postulated for the control of this behaviour: external sensory information (perception of sex pheromone) releases courtship, proprioception from the legs is required to curtail turning when the specified turn angle is reached, and internally stored information determines the sign of turning and patterns the courtship actions.     

The effects of cross-fostering on the behaviour of two species of North American lemmings, Dicrostonyx groenlandicus and Lemmus trimucronatus: I. Olfactory preferences

To determine the role of the maternal environment in the development of adult olfactory preferences, the young of two species of North American lemmings (Dicrostonyx groenlandicus and Lemmus trimucronatus) were reciprocally cross-fostered shortly after birth. In-fostered (reared by foster conspecific females) and non-fostered animals served as controls. When adult, subjects were tested for olfactory preferences in a free-choice Y-maze olfactometer. When compared to controls, cross-fostered animals showed increased preference for heterospecific odour. This effect was stronger for males than for females. These results suggest that adult species-specific odour preferences are learned during the neonatal period.     

Inhibition of the pancreatic microsome enzyme release phenomenon by inhibitors of signal peptidase activity

The protease-sensitive release of α-amylase from rat pancreatic microsomes, incubated at 37°C, was inhibited by protease inhibitors which have been reported to inhibit signal peptidase activity. Protease inhibitors which did not affect signal peptidase activity also failed to inhibit amylase release from microsomes. Although the observed amylase release was in the opposite direction to enzyme secretion and involved fully-synthesised proteins, rather than nascent peptides, it is proposed that the enzyme release phenomenon reported from this laboratory (Pearce et al. (1978) Biochem. J. 176, 611–614) is related to the protein transporting mechanism involved in secretion.     

Subpopulations of splenic T and B lymphocytes producing and regulating leukocyte adherence inhibition factor

Picryl chloride induces contact hypersensitivity in mice, accompanied by spleen cell sensitization that is demonstrable in vitro by specific antigen-induced formation of leukocyte adherence inhibition factor (LAIF). This cellular activity was detected only up to 7 days after sensitization; thereafter the spleen cells appeared to be unreactive with the antigen. The cells were still normally reactive with the mitogen concanavalin A. Antigen reactivity of such “late” cells was restored by passage through a glass-bead column (provided resulting nonadherent cells were reconstituted with normal macrophages), and the restored reactivity was again suppressed by the eluted glass-bead-adherent cells. Suppression was antigen specific. Separation of T and B lymphocytes by affinity chromatography, after glass-bead treatment of sensitized spleen cells, showed that two subpopulations of B cells—those responsible for producing LAIF as well as those suppressing LAIF production by T cells—were glassbead adherent. This was extended by showing directly with anti-Thy-1.2 serum that B cells producing LAIF and suppressor T cells were glass adherent. Thus two suppressive cell populations, and the B cell producing LAIF, were glass adherent while the T-cell LAIF producer was not. Tests for adoptive transfer of cutaneous hypersensitivity in vivo demonstrated the relevance of many of the above observations to conditions in the whole animal. “Late” spleen cells from sensitized mice could not transfer hypersensitivity but this property was restored by glass-bead passage. The eluted adherent cells suppressed transfer. Both adoptive transfer and its suppression were antigen specific.     

Density, distribution and mobility of surface anions on a normal/transformed cell pair

The distribution and mobility of cell surface anions was investigated on low passage cultures of secondary BALB/c embryonic fibroblasts and their SV40-transformed counterparts (VLM cells) using polycationized ferritin (PCF) as a label. While the absolute number of anions/nm² of membrane was equivalent on the two cell types, the topographical distribution and mobility of these anions was strikingly different. After pulse-labeling with PCF at 37 °C, anions on BALB/c fibroblasts occurred in large piled-up clusters separated by extensive areas of membrane ( = 0.47 μm) free of negative charges. Labeling at 4 °C reduced the degree of “piling up” within the clusters, but the intercluster spacing was maintained indicating that the anions have short-range mobility in the membrane and can be cross-linked into a tight lattice at 37 °C. These anions do not, however, demonstrate any long-range mobility during a 20 min post-label incubation in PBS. In contrast, anions on VLM cells are inherently present in a random configuration of microclusters and single anions with relatively small ( = 0.09 μm) intervening areas of low charge density. Short-range mobility of surface anions is not displayed, presumably as a result of the inter-site distance, but long-range mobility is indicated by the formation of large site clusters following a 20 min incubation in PBS after pulse-labeling. Very mild proteolysis of BALB/c fibroblasts induces a change in the topography of surface anions toward the random configuration typical of VLM cells. These data are discussed in relation to altered social interactions between tumor cells which may be influenced by cell-cell adhesion characteristics.     

A technique for quantitating enzyme histochemistry in adjuvant arthritic joints. II. Acid phosphatase

Synopsis This paper reports on the incorporation of acid phosphatase histochemistry with a quantitative technique designed to measure the percentage of histochemically-localized enzyme-reactive cells found in adjuvant arthritic articular cartilage, synovial membrane and bone marrow. With the data presented and the comparisons made, this incorporation is validated and adjuvant arthritic acid phosphatase lesions established. In addition to discussing the importance of the histochemical data and its relationship with intra-articular lysosomes, the applicability of the reactive cell values to drug inhibition studies is discussed.     

Distribution and movement of toxaphene in anaerobic saline marsh soils

The biological oxygen demand (BOD) of filtered water from Lake Wingra, Wisconsin is significantly higher in the littoral zone than in the pelagial zone. Laboratory experiments indicate that BOD is not influenced by water temperature at the time of sampling or by enrichment with nitrate or ammonia. Rather, enrichment with macrophyte leachate sharply increases BOD, and enrichment with phosphate produces a small but significant increase in BOD. We conclude that high BOD in littoral waters of the lake is an indication of production of labile organic matter in the water by dense beds of the macrophyte Myriophyllum spicatum.