Prostaglandin F and progesterone secretion by porcine endometrium and corpus luteum in vitro

Slices of porcine endometrium and corpus luteum tissue obtained from mature sows throughout the luteal phase of the oestrous cycle were incubated in culture medium which was analysed at regular intervals over a period of 8 hours for prostaglandin F and progesterone. Prostaglandin F secretion was greatest by endometrium obtained during the mid III to late I luteal stage of the cycle and the increased levels secreted by this tissue were paralleled by high levels of secretion from corpus luteum tissue. The addition of indomethacin (10 μg/ml) to the culture medium completely abolished prostaglandin F secretion by both endometrium and luteal tissue indicating that the high levels of the prostaglandin were due to synthesis. Progesterone secretion by the corpus luteum was maximal from early luteal tissue and had declined to considerably lower levels by late stage tissue when prostaglandin secretion was greatest. The possible physiological significance of luteal prostaglandin F secretion is discussed.     

The interaction of egg yolk and ram spermatozoa studied with a fluorescent probe.

The flourescent membrane marker, 1-anilinoaphtalene-8-sulphonate (ANS) was used to investigate the attachment of egg-yolk to the plasma membranes of ram spermatozoa. The degree of fluorescence was assessed using a subjective scoring system. It was found that egg yolk competes with ANS for sites on the plasma membrane. When the diluent contained 10% egg yolk, no ANS could be detected on the membranes. Egg yolk attached to the plasma membrane could be removed by washing twice with a yolk-free diluent. Loss of sperm motility in the presence of ANS was observed but some spermotozoa remained motile after incubation at 37 degrees C for 15 min with 2mM-ANS. Egg yolk protected spermatozoa against this loss of motility. It is suggested that egg yolk protects spermatozoa during chilling and freezing by its attachment to the sperm plasma membrane.     

Integrated physiological units in plants

Plants, like animals, have traditionally been viewed by ecologists and evolutionary biologists as fully integrated organisms capable of sharing energy, nutrient and water resources throughout their bodies. Recent studies, however, indicate that many plants may be more realistically considered to be assemblages of semiautonomous integrated physiological units (IPUs)(1), consisting of physiological(2) as well as morphological subunits(3). The existence of IPUs may have important implications for the study of herbivore, frugivore and pollinator interactions with plants, as well as for studies of patterns of resource distribution that require understanding of the environmental regulation of plant development.     

Construction of a representative cDNA library from mRNA isolated from mouse oocytes

A representative cDNA library has been constructed from the small quantities of poly(A)+ RNA present in unfertilised mouse oocytes. The construction of this library has been achieved by use of cow pea mosaic virus RNA as a carrier during isolation of polyadenylated message and during subsequent cloning procedures. This approach may be applicable to any system in which amounts of mRNA are limiting.     

Host-parasite relationships among group A streptococci. IV. Suppression of antibody response by streptococcal pyrogenic exotoxin

In rabbits, purified streptococcal pyrogenic exotoxin, at 0.002 of the ld(50) dose, suppressed the antibody response to injected sheep erythrocytes. The antibody suppressed was determined by density gradient ultracentrifugal analysis to be of the 19S class. Background serum antibody (50% hemolytic units), as determined photometrically, correlated well with background antibody-forming spleen cells, as determined by the hemolytic-plaque technique. The exotoxin induced neither positive nor negative changes in background antibody levels, but suppressed the early secondary response to injected antigen. A comparison and control experiment showed that purified gram-negative bacterial endotoxin at identical protocol did not induce antibody suppression, but did induce the well-known adjuvant effect. Because streptococcal pyrogenic exotoxin is known to inhibit the phagocytic function of the reticuloendothelial system (RES), these data strongly support the concept that antigen is processed by cells of the RES before it evokes a secondary immune response. The results also demonstrated that streptococcal pyrogenic exotoxin may play a unique role in lowering the acquired defense of the host against infection. If the anamnestic immune response of the host is temporarily suppressed, then the host-parasite balance would be upset in favor of the parasite.     

The Changes in Fluorescence of Acridine Orange-Stained Hela Cells During Ultraviolet Illumination

HeLa cells were stained with a 1/12,000 concentration of acridine orange at pH 7.2 for 3 min and the fluorescence emission was measured quantitatively for effects of ultraviolet illumination with durations including intervals between 5 and 210 min. The total photometric fluorescence intensity increased for the first 30 min, then decreased with illumination time. The initial maximum fluorescence intensity occurred at 525 nm and shifted progressively to shorter wavelengths. Fluorescence intensity above 580 nm decreased with increasing duration of illumination time while that below 580 nm showed an initial increase in intensity followed by a gradual fading.     

The preparation and biological activity of novel amino acid analogs of butirosin

The aminoglycoside antibiotic butirosin (1) has been chemically modified in its amino acid side-chain. The (S)-()-4-amino-2-hydroxybutyryl side-chain was removed by alkaline hydrolysis of the tetrakis(5,5-dimethyl-3-oxo-1-cyclohexen-1-yl) derivative. The resulting deacylated, trisubstituted derivative 3 was reacylated with a wide variety of mono and polyfunctional amino acids. The cyclohexenyl protecting groups were then removed by chlorine gas and the new analogs isolated chromatographically. Structure-activity relationships were determined with five microorganisms, including Pseudomonas aeruginosa. The specific side-chain structures that exhibited maximum potency against Pseudomonas are identified.Butirosin¹, a new aminoglycoside antibiotic complex produced by mucoid strains of Bacillus circulans NRRL B-3312 and B-3313, is the first example of the aminocyclitol class of compounds to contain an amino acid in its chemical structure. Complete structural assignments for butirosin A and B have been described² and are shown in formula 1. The amino acid, which is connected by an amide linkage to N¹ of the deoxystreptamine moiety, was found to be the unique (S)-()-4-amino-2-hydroxybutyric acid². The butirosins have marked activity against Gram-positive and Gram-negative bacteria, including Pseudomonas aeruginosa, both in vitro and in vivo, as well as low toxicity in mammalian species^3,4. They were therefore likely candidates for structural-modification studies.     

Liquid scintillation counting of radioactive monomeric and polymeric carbohydrates on paper chromatograms

A simple, improved scintillation counting procedure was developed for the assay of radioactive mono- and polysaccharides on paper chromatograms. Segments of chromatograms are placed in scintillation vials and soaked in water to completely elute the carbohydrate before addition of Aquasol, a xylene-based scintillation fluid. The resulting water-Aquasol solution is counted in a liquid scintillation counter. Evaluation of numerous experimental variables revealed optimal conditions for complete elution of mono- and polysaccharides with water before counting in Aquasol.The water elution-Aquasol procedure allows water-soluble substances (¹⁴C- and ³H-labeled) on paper to be assayed with increased accuracy and sensitivity (three- to fivefold improvement in counting efficiency of tritiated samples). The simplicity of the procedure allows entire radiochromatograms to be assayed readily.