Pathological changes in the nephrocytes of the shore crab, Carcinus maenas, following injection of bacteria

The gills of Carcinus maenas were examined by light and electron microscopy following injection of either sterile saline or the bacteria Bacillus cereus and Moraxella sp., to determine any role(s) for the nephrocytes in the host defense reactions. The results showed that although intact bacteria were not sequestered to the nephrocytes, these cells were active in the removal of large quantities of cell debris from the hemolymph. Much of this material was derived from the breakdown of the hemocytes in response to the presence of bacteria and it's accumulation in the central vacuoles of the nephrocytes resulted in the degradation of these cells. It is proposed that while nephrocytes do not phagocytose intact bacteria, they augment the host defenses by clearing much of the hemocyte and associated bacterial debris from the gills, thus preventing blockage of the lamellar sinuses and subsequent impairment of respiration.     

Effect of human leukocyte interferon on human lymphocytes in vitro: cytogenetic studies

Mitogen-stimulated lymphocytes from 8 healthy donors were exposed to interferon, and cytogenetic studies were preformed. The response of lymphocytes to the mitogens phytohemagglutinin (PHA), concanavalin A (con A) and pokeweed mitogen (PWM) was inhibited by interferon, whereas an increased number of structural chromosomal aberrations was not detected. Further investigations of the cytogenetic effects of interferon are needed.     

Cellular defense reactions of the shore crab, Carcinus maenas: in vivo hemocytic and histopathological responses to injected bacteria

The cellular defense reactions of the shore crab, Carcinus maenas, were studied, following injections of the bacteria Bacillus cereus and Moraxella sp., by histological and ultrastructural examination of the gills, heart, and hepatopancreas. The majority of the bacteria were sequestered to the gills, but some were also later evident in the heart and hepatopancreas. The presence of the bacteria in the gills initiated the formation of numerous small cell clumps, composed of both refractile and phagocytic cells, which entrapped many microorganisms. The clumps reached a maximum size 6 hr after inoculation and although some were cleared from the gills others persisted for 7 days, becoming more compact and necrotic during this period. Clump formation appears to occur following recognition of the bacteria as foreign and results in the hemocytes becoming sticky and adherent. The response is very effective in rapidly immobilizing the bacteria, thus restraining the spread of infection. It is proposed that this phenomenon may be a significant component of crustacean cellular host defenses.     

Sigma factor is not released during transcription in Bacillus subtilis

Molecular Genetics and Genomics - The relationship between sigma (σ) and delta (δ) factors of Bacillus subtilis RNA polymerase has been analyzed during initiation of RNA synthesis. When...     

Induction by ouabain of hemoglobin synthesis in cultured friend erythroleukemic cells

Induction of erythroid differentiation in ouabain-resistant murine erythroleukemia cells by ouabain is reported. Ouabain induction results in the appearance of hemoglobin-containing cells 12–24 hr earlier than induction of the same clone by dimethyl sulfoxide. The levels of globin mRNA after ouabain induction are similar in amount to the globin mRNA levels observed after induction by dimethyl sulfoxide. The concentration of ouabain required to induce hemoglobin synthesis depends upon the K⁺ ion levels in the culture medium. Lowering the extracellular K⁺ ion concentration 2–4 fold reduced by 10–40 fold the ouabain concentration necessary for the induction of hemoglobin synthesis. In low K⁺ medium (1.8 mM), ouabain is an effective inducer of hemoglobin synthesis at a concentration of 0.02 mM. This K⁺ effect is specific for ouabain induction, since induction by other inducers, such as dimethyl sulfoxide and dimethyl acetamide, does not exhibit this marked sensitivity to the levels of K⁺ ions in the culture medium. These results suggest that the binding of ouabain to the plasma membrane enzyme, $\text{Na}\text{K}$ ATPase, is required for the induction of erythroid differentiation by ouabain. A small but significant proportion of wild-type, ouabain-sensitive cells also can be induced by ouabain, below ouabain concentrations that are toxic to these cells. The observation that the binding of ouabain to the $\text{Na}\text{K}$ ATPase induces hemoglobin synthesis suggests that changes in the intracellular concentration of K⁺ ions may be involved in the control of erythroid differentiation in Friend erythroleukemic cells.     

Ethylene and IAA transport in potato

Although elongation growth is reduced by ethylene, swelling responses do not occur. Ethylene reduces neither transport nor metabolism of applied IAA in either mesocotyl or coleoptile. We propose that maintenance of high auxin levels within these tissues sustains polar transport and contributes to the relative insensitivity of maize to applied ethylene.     

C2 deficiency in man. genetic relationship to a mixed lymphocyte reaction determinant (7a*)

Three unrelated individuals with, respectively, lupus erythematosus, polyarteritis, and membranoproliferative glomerulonephritis and totally deficient in the second component of complement are demonstrated to be mutually poorly reactive in mixed lymphocyte culture and homozygous for the mixed lymphocyte reaction determinant (MLR-S or LD) short 7a (7a^*). The gene controlling the elaboration of C2 in man is shown to be separate from, and probably to map outside of, the second locus ofHL-A and theMLR-S locus. Genetic linkage disequilibrium is strongly suggested between HL-A 10, W18, 7a^*, and C2 deficiency.     

The zinc,copper, and manganese status of children with malabsorption syndromes and inborn errors of metabolism

The zinc, copper, and manganese status of seven children with malabsorption syndromes of varied etiology (MVE) and 12 with inborn errors of metabolism (IEM) receiving semi-synthetic diets was investigated using serum and hair trace element concentrations, dietary trace element intakes, and anthropometric measurements as the principal indices. The hair zinc levels of both test groups and hair manganese levels of the IEM group were significantly lower (p<0.05) than those of their respective healthy controls matched by age, sex, and geographic location, despite comparable dietary zinc and manganese intakes in test and control subjects. Four subjects from the malabsorption and five from the inborn errors group had hair zinc levels below 100 μg/g (range 30–88 μg/g). Of these nine subjects, serum zinc levels were determined for six, and five were less than normal (range 64–74 μg/dL). In contrast, the copper status of the MVE and IEM subjects, as indicated by hair and dietary copper levels, was not lower than the controls. Mean serum copper levels were 136±30 and 171±40 μg/dL for the IEM and MVE groups, respectively. Levels for the MVE subjects were higher than published normal values. The suboptimal zinc and manganese status observed in some of these test subjects probably arose from malabsorption and decreased availability of dietary zinc and manganese. However, the zinc depletion was not severe enough to result in linear growth retardation.