Pregnancy and ovulation rates in Grey seals (Halichoerus grypus) on the British coast

This study determined the pregnancy and ovulation rates in two stocks of Grey seals from Britain and described changes in pregnancy and ovulation rate with age. Seals sampled from the Hebrides during August 1978 and from the Fame Islands between March 1979 and October 1981 were used. Adult female pregnancy rate in the stock from the Fame Islands was estimated to be 94–29%, compared with 82–95% for seals from the Hebrides. These values were not significantly different. Pregnancy rate estimated by direct observation of a conceptus was comparable with an estimate from the presence or absence of corpora albicantia in the ovaries. By the age of four years and over (4 +), i.e. at maturity, 50% of females became pregnant. Pregnancy rate remained constant from age 5 + onwards. Pregnancy rate amongst females which became sexually mature at a younger than average age was lower than in older age classes.     

Effects of temperature and CO2 enrichment on kinetic properties of phospho-enol-pyruvate carboxylase in two ecotypes of Echinochloa crus-galli (L.) Beauv., a C4 weed grass species

Summary Two populations of Echinochloa crus-galli (Québec, Mississippi) were grown at the Duke University Phytotron under 2 thermoperiods (28°/22°C, 21°/15°C day/night) and 2 CO₂ regimes (350 and 675 l l^-1). Thermostability, energy of activation (E _a ),K _m (PEP), K _m (Mg⁺⁺), and specific activity of phospho-enol-pyruvate carboxylase (PEP_c) were analyzed in partially purified enzyme preparations of plants grown for 5 weeks. Thermostability of PEP_c from extracts (in vitro) and leaves (in situ) was significantly higher in Mississippi plants. In vitro denaturation was not appreciably modified by thermal acclimation but CO₂ enrichment elicited higher thermostability of PEP_c. In situ thermostability was significantly higher than that of in vitro assays and was higher in Mississippi plants acclimated at 28°/22°C and in plants of the two ecotypes grown at 675 l l^-1 CO₂. E _a (Q ₁₀ 30°/20°C) for PEP_c was significantly lower in Québec plants as compared to Mississippi and no acclimatory shifts were observed. Significantly higher K _m's (PEP) in 20°C assays were obtained for Mississippi as compared to Québec plants but values were similar at 30°C and 40°C assays. K _m (Mg⁺⁺) decreased at higher assay temperatures and were significantly lower for PEP_c of the Québec ecotype. No significant changes in K _m (Mg⁺⁺) values were associated with modifications in temperature on CO₂ regimes. PEP_c activity measured at 30°C was significantly higher for Québec plants when measured on a leaf fresh weight, leaf area or protein basis but not on a chlorophyll basis. Significantly higher PEP_c activity for both genotypes was observed for plants acclimated at 21°/15°C or grown at 675 l l^-1 CO₂. Net photosynthesis (Ps) and net assimilation rates (NAR) were higher in Québec plants and were enhanced by CO₂ enrichment. NAR was higher in plants acclimated at low temperature, while an opposite trend was observed for Ps. PEP_c activities were always in excess of the amounts required to support observed rates of CO₂ assimilation.     

Selection of a dye for use in semen transport studies in the cow

A series of experiments was carried out to select a dye and diluent that would facilitate identification of bovine inseminate in the uterus of the live cow when using hysteroscopic techniques. Of the dyes tested, Aniline Blue and the permitted food dye Green S as 1% solutions were the most suitable when added to semen with milk buffer diluent. Neither stained the uterine mucosa nor adversely affected the equipment, and both were visually distinctive during hysteroscopy. Using 1% concentrations of these dyes, sperm motility scores were acceptable before and after slow and fast freezing processes.     

Complete reductive dechlorination and mineralization of pentachlorophenol by anaerobic microorganisms

Anaerobically digested municipal sewage sludge which had been acclimated to monochlorophenol degradation for more than 2 years was shown to degrade pentachlorophenol (PCP). Di-, tri-, and tetrachlorophenols accumulated when PCP was added to the individual acclimated sludges. When the 2-chlorophenol- (2-CP), 3-CP-, and 4-CP-acclimated sludges were mixed in equal volumes, PCP was completely dechlorinated. The same results were obtained in sludge acclimated to the three monochlorophenol isomers simultaneously. With repeated PCP additions, 3,4,5,-trichlorophenol, 3,5-dichlorophenol, and 3-CP accumulated in less than stoichiometric amounts. All chlorinated compounds disappeared after PCP additions were stopped. All chlorinated compounds disappeared after PCP additions were stopped. Incubations with [14C]PCP resulted in 66% of the added 14C being mineralized to 14CO2 and 14CH4. Technical-grade PCP was found to be degraded initially at a rate very similar to that of reagent-grade PCP, but after repeated additions, the technical PCP was degraded more slowly. Pentabromophenol was also rapidly degraded by the mixture of acclimated sludges. These results clearly show the complete reductive dechlorination of PCP by the combined activities of three chlorophenol-degrading populations.     

The killer toxin of Kluyveromyces lactis: characterization of the toxin subunits and identification of the genes which encode them.

The killer character of the yeast Kluyveromyces lactis is associated with the presence of the linear DNA plasmids k1 and k2 and results from the secretion of a protein toxin into the growth medium. We find that toxin activity co-purifies with three polypeptides which we have termed the alpha- (mol. wt 99,000), beta- (mol. wt 30,000) and gamma- (mol. wt 27,500) subunits. The alpha-subunit appears to contain a single asparagine-linked oligosaccharide chain but neither of the smaller subunits is glycosylated. The N-terminal amino acid sequence of each subunit has been determined. Comparison of these data with the DNA sequence of plasmid k1 indicates that it encodes all three subunits. The alpha- and beta-subunits must be processed from the primary translation product of a single gene by an enzyme related to the KEX2 endopeptidase of Saccharomyces cerevisiae.     

A comparison of anionic sites in the glomerular basement membranes from different classes of fishes

Summary Cationized ferritin was injected into the circulatory system of teleosts, the sea raven and Atlantic eelpout, and into elasmobranchs, the spiny dogfish and the skate, to determine if the glomerular basement membranes (GBM) from these different groups of fishes possess anionic binding sites similar to those present in the GBM of mammals. The distribution of cationized ferritin was the same in all fishes listed. Cationized ferritin was localized only in the GBM and the mesangial matrix. The regular distribution of cationized ferritin within the laminae rarae (60 nm intervals) was taken as evidence of the presence of anionic binding sites. Cationized ferritin did not bind to the glomerular capillary endothelium, nor was any of it localized at the base of the slit diaphragms of the foot processes of the podocytes. The distribution of binding sites in the GBM of these fishes is similar to that in another teleost, the winter flounder, and in a cyclostome, the hagfish.     

Localization of a substance P-like material in the central and peripheral nervous system of the snail Helix aspersa

Summary A monoclonal antibody against substance P was used for immunocytochemical staining of the central ganglia of the snail Helix aspersa and several peripheral tissues including the gut, reproductive system, cardiovascular system, tentacle and other muscles.Within the central ganglia many neurones, and many fibres in the neuropile and the nerves entering the ganglia, were stained for the SP-like material. The largest numbers of reactive cell bodies were in the pleural ganglia and on the dorsal surfaces of the pedal ganglia. A group of cells was also found, surrounding the right pedal-cerebral connective, that did not fluoresce, but were enveloped by reactive processes terminating directly onto the neurone somata.Specific staining was observed in all peripheral tissues examined and always appeared to be concentrated in nerve terminals. Most particularly these occurred in the heart and aorta, the pharyngeal retractor muscle and the tentacle. Although mostly present in muscular tissues, some fluorescence was also observed in the nervous layer surrounding the retina. The tentacular ganglion also contained immunoreactive cell bodies.     

Anaerobic biodegradation of phenolic compounds in digested sludge.

We examined the anaerobic degradation of phenol and the ortho, meta, and para isomers of chlorophenol, methoxyphenol, methylphenol (cresol), and nitrophenol in anaerobic sewage sludge diluted to 10% in a mineral salts medium. Of the 12 monosubstituted phenols studied, only p-chlorophenol and o-cresol were not significantly degraded during an 8-week incubation period. The phenol compounds degraded and the time required for complete substrate disappearance (in weeks) were: phenol (2), o-chlorophenol (3), m-chlorophenol (7), o-methoxyphenol (2), m- and p-methoxyphenol (1), m-cresol (7), p-cresol (3), and o-, m-, and p-nitrophenol (1). Complete mineralization of phenol, o-chlorophenol, m-cresol, p-cresol, o-nitrophenol, p-nitrophenol, and o-, m-, and p-methoxyphenol was observed. In general, the presence of Cl and NO2 groups on phenols inhibited methane production. Elimination or transformation of these substituents was accompanied by increased methane production, o-Chlorophenol was metabolized to phenol, which indicated that dechlorination was the initial degradation step. The methoxyphenols were transformed to the corresponding dihydroxybenzene compounds, which were subsequently mineralized.     

Replication of nucleolus-associated DNA during "G2 phase" in Physarum polycephalum

In the myxomycete, Physarum polycephalum, the bulk of nuclear DNA replication occurs during a period of a few hours immediately following upon mitosis. During the remainder of the intermitotic period, incorporation of thymidine-³H continues at a low rate in the region of the nucleolus (radioautographs). A few nuclei incorporated thymidine-³H into the extranucleolar chromatin at a high rate at all times of the intermitotic period. These nuclei were exceptionally large and they frequently contained several small nucleoli of different sizes rather than the one, central nucleolus which is characteristic of a normal interphase nucleus.