Environmental stress and bacterial infection in channel catfish, Ictalurus punctatus Rafinesque

Channel catfish, Ictalurus punctatus , were injected intraperitoneally with a sublethal dose of Aerornonas hydrophila and then stressed for 144 h by being maintained either in a dissolved oxygen concentration of 1·5 mg/1, 1·2 mg/1 total ammonia, and/or 6·5 mg/1 free CO₂ with a continuous inflow of water. A significant difference in percentage of mortality was noted between treatments ( P < 0·05). The trunk kidneys of surviving stressed fish had significantly higher total bacterial counts than non-stressed controls. A. hydrophila was isolated from 67% of the stressed fish and 9% of the control fish. Edwardsiella tarda , apparently endemic in the population, was isolated from 43% of the stressed fish and 7% of the control fish. Histopathological lesions were in the gills, liver, spleen, trunk kidney, and head kidney of stressed fish, but not control fish.     

Factors influencing the fecundity of Moniliformis moniliformis (Acanthocephala): constant diet and varied dose

Aspects of the reproductive performance of Moniliformis moniliformis were investigated in rats allowed to feed ad libitum on a purified diet containing 1% (w/w) fructose as an energy source for the worms. The rats were infected with either 10, 20, 40 or 80 cystacanths each with the intention of investigating density-dependent effects on worm fecundity. The establishment of the worms in the gut was independent of dose, but survival, growth and reproductive performance generally were shown to be related to the infective dose given to the rats. The effects could not be related to the absolute numbers of worms present in the small intestine at post-mortem examination. In general, some unidentified regulatory process appeared to operate to create severe density-dependence in survival so that surviving parasites were not present in numbers expected to generate competition. Attainment of sexual maturity, growth and the production of mature eggs by worms from rats given doses of 80 cystacanths each were delayed compared with worms from rats given the other doses, but eventually the performance of the high-dose worms caught up. Worms attached more anteriorly in the small intestine grew bigger and produced more mature eggs. Possible mechanisms responsible for the observed effects are discussed.     

Dissociation of lepidopterous tissues with proteolytic enzymes: Comparison of collagenase,trypsin, and pronase

The fat body and certain other tissues of lepidopterous larvae and diapausing pupae can be completely dissociated by incubation in crude or purified collagenase. Damage to the cells is minimal. Dissociation with trypsin is incomplete, and pronase causes extensive damage. All three enzymes act principally by digesting the extracellular connective sheath that envelops the individual lobes of fat body, since the cells at this stage are not intrinsically cohesive. The experimental findings support the notion that collagen is an important structural component of insect connective membranes.     

PATTERNS OF ALLOZYME DIVERSITY IN THE WEST INDIES CYCAD ZAMIA PUMILA (ZAMIACEAE)

The West Indies cycad, Zamia pumila, is restricted to the Greater Antilles, northern Bahama Islands, Florida, and the southeastern coast of Georgia. An electrophoretic study based on nine enzymes compared 21 accessions from throughout the range of the species. Lower levels of intrapopulation variation than those reported for ferns, other gymnosperms, and angiosperms were discovered for the two more extensively sampled populations. However, this variation was similar to that found in other island taxa and in the endemic Australian cycad, Macrozamia communis. In contrast, allozyme divergence among accessions of Z. pumila appeared relatively high, mostly as a result of rare alleles restricted in geographic distribution. The age and biogeography of Z. pumila may gave contributed to population differentiation. Also, mean number of alleles per locus was low for the species (1.75). Finally, the time-since-divergence value (10.8 million years ago) between Z. pumila and its closest extant relative, Z. splendens, was much smaller than the age of Z. pumila suggested by the fossil record and historical geology of the Caribbean (30–60 million years ago). Together, these data indicate that biochemical evolution within this species, and perhaps in all cycads, is slow when compared to that of noncycad seed plants.     

Tartrate-resistant acid phosphatase in bone and cartilage following decalcification and cold-embedding in plastic

Tartrate-resistant acid phosphatase (TRAP) has been proposed as a cytochemical marker for osteoclasts. We have developed an improved technique for the localization of TRAP in rat and mouse bone and cartilage. This procedure employs JB-4 plastic as the embedding medium, permits decalcification, and results in improved morphology compared with frozen sections. Peritoneal lavage cells were used to determine the appropriate isomer and concentration of tartrate necessary for inhibition of tartrate-sensitive acid phosphatase. After incubation in medium containing 50 mM L(+)-tartaric acid, osteoclasts and chondroclasts were heavily stained with reaction product. On the basis of their relative sensitivity to tartrate inhibition, three populations of mononuclear cells could also be distinguished. These three populations may represent: heavily stained osteoclast/chondroclast precursors; sparsely stained osteoblast-like cells lining the bone surface; and unstained cells of monocyte-macrophage lineage. Our results are consistent with the use of TRAP as a histochemical marker for study of the osteoclast.     

Humoral factors released during trauma ofAplysia body wall

1. Preliminary, general chemical characteristics of substances in artificial sea water (ASW) washed through stimulated body wall (SBW) and in hemolymph taken from noxiously stimulated animals (SHL) were consistent with those of classical neurotransmitters, amino acids, and small- to medium-sized peptides. 2. 5-Hydroxytryptamine (5HT) and acetylcholine (ACh), unlike SBW and SHL, caused relaxation when perfused into isolated body wall. FMRFamide produced a biphasic response--brief contraction followed by prolonged relaxation. 3. Small cardioactive peptide (SCPB) caused body wall contractions similar to those produced by SBW and SHL, except that SCPB contractions displayed more desensitization and were completely blocked by 30 mM CoCl2. SCPB and SBW contractions were synergistic. 4. Dopamine caused persistent body wall contractions similar to those of SBW and SHL. Dopamine contractions were reduced but not blocked by 30 mM CoCl2. Unlike SBW activity, dopamine activity was reduced by alkalinization. 5. Glutamate and taurine produced strong but usually short-lasting body wall contractions. Adenosine, octopamine, arginine vasotocin, and cholecystokinin (CCK-8) caused weak or variable contractions. Met-enkephalin and somatostatin caused no obvious body wall responses. 6. When superfused over the fully sheathed abdominal ganglion, FMRFamide, met-enkephalin, glutamate, aspartate, and taurine reduced the magnitude of the gill-withdrawal reflex elicited by siphon nerve stimulation. 7. Taken together with earlier results, these data suggest a preliminary framework for trauma signal pathways. It is proposed that stress hormones (perhaps including FMRFamide, SCPs, 5HT, and dopamine) are released into hemolymph from neuroendocrine cells. Effective amounts of active intracellular solutes such as amino acids may also be released by extensive cellular rupture. Various humoral signals produce slow effects that contribute to hemostasis, balling up, increased cardiac output, and reflex suppression.     

Historical overview on domesticated plants in China with special emphasis on the Cucurbitaceae

Cultivation of plants in northern China began at an early date. A number of domesticates were derived from native species, and others were introduced from southeastern Asia. Many vegetable species are included in myths and stories of ancient China. These traditional stories, as well as ancient agricultural and medicinal books, often mention cultivated members of the Cucurbitaceae. Twelve genera and 18 species of cucurbits are currently under cultivation in China. A number of them appear to be endemic to Indochina, while others were introduced from Western Asia and the New World. A recent trip to China and a survey of Chinese literature indicated that many cucurbits are consumed in the immature state as vegetables, some are eaten as fruits, and various species are used for medicine and a variety of other purposes. Resumen histórico de las plantas domésticas de la China con énfasis en las Cucurbitaceae. El cultivo de las plantas comenzó en una edad temprana en el norte de China. Varias plantas domésticas fueron derivadas de especies nativas, mientras que otras fueran introducidas desde el sudeste de Asia. Las historias y los mitos de la China antiqua cuentan de diversas especies vegetales. Estos relatos tradicionales, tanto como los viejos libros de las agricultura y medicina, frecuentemente mencionan los miembros cultivados de las Cucurbitaceae. Hoy en día se cultivan doce géneros y dieciocho especies de las familia en la China. Algunas Cucurbitaceae parecen ser endémicos de la Indochina, mientras que otras fueron introducidas desde el oeste de Asia y del Nuevo Mundo. Un viaje reciente a la China y un estudio de la literatura China indicaron que muchas Cucurbitaceae son consumidas en el estado inmaduro, algunas son comidas como frutas, y varias especies son utilizadas en medicina otros propósitos.