Methanogenic Activity and Structural Characteristics of the Microbial Biofilm On a Needle-Punched Polyester Support

In a downflow stationary fixed-film anaerobic reactor receiving a swine waste influent, few bacteria were observed to be tightly adherent to the surfaces of the needle-punched polyester support material. However, there was a morphologically complex, dense population of bacteria trapped within the matrix. Frequently large microcolonies of a uniform morphological type of bacteria were observed. These were particularly evident for methanosarcina-like bacteria which grew forming large aggregates of unseparated cells. Leafy deposits of electron-dense, calcium- and phosphorus-enriched material coated the polyester matrix and some cells. As the biofilm matured there was more extensive mineral deposition which completely entrapped cells. The entrapped cells appeared to autolyze, and many were partially degraded. Further impregnation of the matrix with minerals and apparent cell death may eventually have a deleterious effect on the methanogenic activity of the biofilm.     

Different Sensitivities of Granulocyte-Macrophage and Erythroid Progenitor Cells of Normal Human Bone Marrow to S-Phase-Specific Agents

The extraordinary sensitivity of early erythroid progenitor cells (BFU-e) of normal human bone marrow to tritiated thymidine ([³H]TdR) was studied. While exposure of bone-marrow cells to [³H]TdR for 1 hr resulted in the death of only 40% of the granulocyte-macrophage progenitor cells (CFU-c), 90% of BFU-e were killed. Experiments in which normal bone-marrow cells were mixed with bone-marrow cells which had been exposed to [³H]TdR demonstrated that the excessive killing of BFU-e by [³H]TdR reflected carry-over of the [³H]TdR by the exposed cells. A carry-over effect was not observed for CFU-c, suggesting the presence of a fundamental difference in the metabolism of TdR between CFU-c and BFU-e. There was a suggestion of a carry-over effect regarding two other S-phase-specific agents, hydroxyurea and 1-β-D-arabinofuranosylcytosine.     

Comparison of chemical properties of purified plasma membranes and secretory vesicle membranes from the bovine adrenal medulla

Summary A highly enriched fraction of plasma membranes from the bovine adrenal medulla has been isolated by differential and sucrose gradient centrifugation. The membranes were found to occur as 0.1–0.5 diameter vesicles and to equilibrate at a density of 1.13–1.14 g/ml. This fraction was characterized by 4-fold elevated levels of adenylate cyclase and 20-fold elevated levels of 5-nucleotidase. Secretory vesicle membranes, isolated by repeated hypotonie and hypertonic shocks of whole vesicles, were found to equilibrate between d = 1.08 and d = 1.12 on a sucrose density step gradient. These membranes were highly enriched in cytochrome b₅₆₂ and dopamine--hydroxylase. Proteins in the two membranes were compared by SDS gel electrophoresis. All protein size classes found in the vesicle membrane fraction were also represented in the plasma membrane fraction, though in different proportions on the basis of staining intensity. The plasma membrane fraction contained prominent bands co-migrating with the - and -bands of tubulin, as well as a component co-migrating with actin. These bands were absent from the vesicle membranes. Fingerprint analysis of stained bands from the membrane fraction demonstrated that the components were indeed tubulin and actin. The plasma membranes contained twice as much sialic acid residues as did the chromaffin granule membranes, but had only half the cholesterol content on a weight basis. The cholesterolphospholipid ratio in the plasma membranes was 0.63, while in the secretory vesicle membranes it was 1.04. These results show that plasma membranes and secretory vesicle membranes are functionally and structurally different.Supported, in part, by a stipend to O.Z. from The Grant Foundation, New York     

Phagocytosis and killing of bacteria and yeast by human milk cells after opsonisation in aqueous phase of milk.

Macrophages and neutrophils from human milk phagocytose and kill Staphylococcus aureus and Escherichia coli in vitro after opsonisation by the aqueous phase of milk as effectively as blood leucocytes in serum. They also phagocytose Candida albicans. The overgrowth of E coli resulting from the addition of iron to cultures of the organism in the aqueous phase of milk is not influenced by the presence of cells. We conclude that the phagocytosis and killing of bacteria by milk cells may contribute to the lower incidence of infection among breast-fed than artificially fed babies.     

Lordosis: Inhibiting effects of progesterone in the female rat

Progesterone has two types of inhibitory effects on female sexual behavior that have been well-documented in the guinea pig. The first occurs when high levels of progesterone are present around the start of the estrogen-priming process (“concurrent inhibition”). The second occurs immediately after the display of an estrogen-progesterone-induced period of estrous behavior (“sequential inhibition”). In the present set of experiments, we show that the rat, like the guinea pig, is capable of exhibiting both of these inhibitory effects of progesterone. However, rats require higher doses of progesterone than guinea pigs, at least for concurrent inhibition to be evident. In addition, we show that the dose of progesterone required in a single injection to produce concurrent inhibition is higher than the dose required to produce sequential inhibition in rats. A theory of how progesterone may be accomplishing its inhibitory effects on female sexual behavior in rodents is presented.     

Cyclic antibody formation to polyglycerophosphate in normal and injected rats.

Normal adult Sprague-Dawley rats were bled serially over a 30-week period and their sera were examined for antibodies to polyglycerophosphate (PGP) by a standardized passive hemolysis test. Levels of "natural" antibodies to PGP fluctuated during this period with a majority of animals exhibiting pronounced cycling of serum antibody levels, however, the individual cycles were not synchronized with each other. Feeding of radiolabeled Gram-positive bacilli to these animals and examination of lymphoid tissue by liquid scintillation counting revealed that the antigen persisted mainly in the mesenteric lymph nodes. A second group of rats was injected i.v. with radiolabeled Gram-positive bacilli and tissues were examined for plaque-forming cells (PFC) of PGP specificity, and the sera were examined by passive hemolysis. Cycling of both anti-PGP antibodies and PFC became synchronized in the injected animals with peaks of serum antibody evident at 16 and 28 days post-injection and splenic PFC peaks at 4 and 16 days post-injection. Cycling was also observed in the mesenteric lymph nodes and bone marrow Examination of lymphoid tissue from the rats injected i.v. revealed that antigen introduced by this route also perisisted mainly in the mesenteric lymph nodes, This report demonstrates individual cycling of natural responses to environmental antigen and to the same determinant in secondary responses, indicating its importance as a regulatory mechanism.     

Proteins synthesized by inducer T cells: evidence for a mitogenic peptide shared by inducer molecules that stimulate different cell types

Inducer T lymphocytes synthesize and secrete peptides that stimulate growth and differentiation of many cell types, including lymphocytes and monocytes that kill foreign organisms, B lymphocytes, mast cells and hematopoietic precursor cells. To define these inducer molecules more precisely, we have generated clones of these T cells as a source of homogeneous material for biochemical analysis. These clones synthesize peptides that stimulate T and B cells to divide and that also induce the latter cells to secrete immunoglobulin. Inducer cells synthesize a 14 kilodalton growth polypeptide that stimulates T and B lymphocytes, as well as other cell types, to divide. This 14 kilodalton peptide is normally associated with different, larger peptides that appear to focus its mitogenic activity to one or another target cell.     

The validity of the lead precipitation technique for the localization of ATPase activity in plant cells

Summary The claim that osmium-containing deposits which lack lead are frequently and incorrectly interpreted as enzymatic reaction products in lead precipitation techniques for ATPase localization in plants is without foundation. Proper controls clearly demonstrate the enzymatic origin of membrane-located deposits and the presence of lead is confirmed by analytical electron microscopy.     

The size of the extracellular space in the isolated midgut ofManduca sexta

The size of the extracellular space in the isolated midgut ofManduca sexta measured statically with labeled sucrose and with labeled inulin was 48 and 50 percent of tissue water respectively. Both labeled sulfate and labeled mannitol yielded loading spaces which approached the volume of the tissue water with increasing pulse time and are not valid markers of the extracellular space. A washout method yielded unreliable values for the sucrose and inulin spaces and its use cannot be justified using presently available midgut chamber designs. Values of the sucrose space measured statistically in this study and other studies using different Lepidopteran larvae and different perfusion chambers range from 42 to 48 percent of the tissue water. Agreement between published values of the sulfate space and these values of the sucrose space is fortuitous, the labeling pulses being short enough to yield approximately half saturation of the actual sulfate loading space.