Secretory IgA as a measure of immunocompetence

The field of psychoimmunology has rapidly expanded in recent years and various parameters of the immune system have been examined in relation to psychological factors. The secretory immune system is one of the more interesting aspects of the entire immune system because it protects mucosal membranes from invading organisms. Stress-produced changes in secretory immunoglobulin A (s-IgA) as measured by radial immunodiffusion assays have been reported in several studies. We present three reasons why total s-IgA protein, the measure derived from radial immunodiffusion assays, may not be a reasonable measure of immune system functioning, and we suggest an alternative method for examining secretory IgA that focuses on s-IgA antibody response to a novel antigen.     

Components of pollination effectiveness in Psychotria suerrensis,a tropical distylous shrub

In this paper I report components of effectiveness for pollinators of a tropical distylous shrub, Psychotria suerrensis (Rubiaceae), which is visited by a variety of bees, wasps, and butterflies, and by two species of hummingbirds. In the field, I measured the following components of effectiveness: frequency of visits, evenness of visits across plants, and diurnal pattern of visits. I also used flight-cage experiments to compare pollentransfer abilities of euglossine bees and heliconiid butterflies. Euglossine bees visited more frequently, visited earlier in the day, and visited a higher proportion of plants in the population than did other taxa. In flight cage experiments, bees and butterflies transferred similar amounts of pollen overall, but bees transferred significantly more inter-morph (compatible) pollen. For each component measured, euglossine bees appeared to be the most effective pollinators.     

Mass Coral Reef Bleaching: A Recent Outcome of Increased El Niño Activity?

Coral reefs are generally considered to be the most biologically productive of all marine ecosystems, but in recent times these vulnerable aquatic resources have been subject to unusual degradation. The general decline in reefs has been greatly accelerated by mass bleaching in which corals whiten en masse and often fail to recover. Empirical evidence indicates a coral reef bleaching cycle in which major bleaching episodes are synchronized with El Niño events that occur every 3–4 years on average. By heating vast areas of the Pacific Ocean, and affecting the Indian and Atlantic Oceans as well, El Niño causes widespread damage to reefs largely because corals are very sensitive to temperature changes. However, mass bleaching events were rarely observed before the 1970s and their abrupt appearance two decades ago remains an enigma. Here we propose a new explanation for the sudden occurrence of mass bleaching and show that it may be a response to the relative increase in El Niño experienced over the last two decades.     

Genetic research with nonhuman primates: serving the needs of mankind Symposium summary and future prospects

The wide array of papers delivered at this symposium, ranging from population genetics to molecular genetics, is convincing evidence that genetic research with nonhuman primates is in full bloom. In fact, progress has been quite remarkable considering that a significant number of pedigreed colonies of nonhuman primates have been available for less than 25 years, which is hardly enough time to raise 3 generations of chimpanzees, 5 generations of baboons or 6 generations of rhesus monkeys. Were it not for these pedigreed colonies, we would not have been privileged to have this assemblage of papers on behavior, social structure, predisposition to disease and management of breeding colonies. It is indeed exciting that preliminary evidence has been obtained for major genes that play a role in susceptibility to dyslipoproteinemias in baboons, and that monoclonal antibodies and DNA markers are helping us to understand cholesterol metabolism. And thanks to computers, we can now rank animals in a colony in terms of their useful genotypes as well as their productivity. One can not help but be impressed with the commonality of humans and nonhuman primates at the structural and functional levels. For example, the major histocompatibility systems and the maternal-fetal relationships are very similar. We heard that this similarity is even more striking at the chromosomal, biochemical and DNA levels. A provocative question yet to be answered is, “what accounts for the obvious differences between humans and nonhuman primates in view of these incredible similarities?” In light of these advances, this symposium was at the cutting edge of primate genetics and the papers published in this issue of Genetica are certain to be hallmarks in the literature.     

Infection of macaque monkeys with simian immunodeficiency virus from African green monkeys: virulence and activation of latent infection

The virulence of three isolates of simian immunodeficiency virus from African green monkeys (SIVagm) was studied in rhesus and pigtailed macaques. None of 15 rhesus monkeys and one of four pigtailed monkeys died from infection during the time they were studied (up to 33 months). SIVagm was only isolated from rhesus monkeys for up to 2 months after inoculation. However, when these animals were secondarily infected with Simian acquired immunodeficiency syndrome retrovirus type 1 (SRV-1), SIVagm was activated and isolated. Dual infection caused increased mortality.     

The properties of peptidyl diazoethanes and chloroethanes as protease inactivators

Earlier work has demonstrated the irreversible inactivation of serine and cysteine proteinases by peptides with a C-terminal chloromethyl ketone group. With a C-terminal diazomethyl ketone, on the other hand, peptides become reagents specific for cysteine proteinases. We have now synthesized and examined the properties of reagents with an additional methyl side chain near the reactive grouping with the goal of diminishing side reactions in a cellular environment. Derivatives of neutral amino acids as well as of lysine and arginine have been prepared. The chloroethyl ketones are about 60% less reactive to chemical nucleophiles than the chloromethyl ketones. However, the susceptibilities of the proteases examined varied remarkably. Cathepsins B and L of the papain family of cysteine proteinases were much less susceptible (about 2 orders of magnitude less) to both peptidyl diazoethyl and chloroethyl ketones. In marked contrast, clostripain, a cysteine proteinase of a separate family was decisively more susceptible to chloroethyl ketones. The serine proteinases showed a drop in susceptibility to the chloroethyl ketones generally, and this was similar to the drop in chemical reactivity in proceeding from the chloromethyl to the chloroethyl ketone.     

On the evolution of functional secondary metabolites (natural products)

It is argued that organisms have evolved the ability to biosynthesize secondary metabolites (natural products) because of the selectional advantages they obtain as a result of the functions of the compounds. The clustering together of antibiotic biosynthesis, regulation, and resistance genes implies that these genes have been selected as a group and that the antibiotics function in antagonistic capacities in nature. Pleiotropic switching, the simultaneous expression of sporulation and antibiotic biosynthesis genes, is interpreted in terms of the defence roles of antibiotics. We suggest a general mechanism for the evolution of secondary metabolite biosynthesis pathways, and argue against the hypothesis that modern antibiotics had prebiotic effector functions, on the basis that it does not account for modern biosynthetic pathways.     

四川省西部鱼类寄生粘孢子虫——1.粘体虫属六新种(粘孢子纲:双壳目)

本文报导四川省西部鱼类寄生粘孢子虫粘体虫属六新种,即异型粘体虫,新种Myxosoma disparis sp.nov.,四川粘体虫,新种Myxosoma sichuanensis sp.nov.,光唇粘体虫,新种Myxosoma acrossochilusi sp.nov.鳅粘体虫,新种Myxosoma nemachilusi sp.nov.斜囊粘体虫,新种Myxosoma obliqua sp.nov.,雅安粘体虫,新种Myxosoma yaanensis sp.nov.。     

Production of steroids and release of prostaglandins by spherical pig blastocysts in vitro

Levels of pregnenolone and progesterone in spherical pig blastocysts (near 4 and 15 microM respectively) exceeded respective levels in histotroph by about 400-fold. When blastocysts were cultured for 5 days in a synthetic medium containing pregnenolone sulfate (1 microM), daily rates of release of pregnenolone, progesterone, androstenedione, testosterone, oestrone and oestradiol were determined to be near 320, 45, 26, 27, 0.8 and 9.2 fmol per blastocyst respectively. Daily outputs of progesterone and testosterone (fmol per blastocyst) diminished (P less than 0.05) to 1.3 and undetectable levels (less than 2) respectively in the presence of Trilostane (94 microM). Increasing the content of pregnenolone sulfate in the culture medium (to 4.5 microM) resulted in higher daily rates of release of pregnenolone and progesterone (to near 1740 and 380 fmol per blastocyst respectively), verifying activity of 3 beta-hydroxy-delta 5-steroid dehydrogenase, and of arylsulfatase, in tissues of intact spherical pig blastocysts. Prostaglandin E2 was the predominant prostaglandin (PG) released by cultured blastocysts (about 1 fmol per blastocyst per hour), hourly rates of release of PGH2 (derived) and PGF2 alpha being near 0.1 and less than 0.06 fmol per blastocyst respectively. The data establish a capacity for spherical pig blastocysts to release a range of steroids and PGs of possible significance to embryonic growth and development in vivo.