The ecology and taxonomy of anaerobic halophilic eubacteria

Abstract A number of obligately anaerobic chemoorganotrophic moderately halophilic bacteria have been isolated from the bottom sediments of the Dead Sea and the Great Salt Lake, Utah: (1) Halobacteroides halobius , a long motile rod from the Dead Sea, fermenting sugars to ethanol, acetate, H₂ and CO₂; (2) Clostridium lortetii , a rod-shaped bacterium from the Dead Sea, producing endospores with attached gas vacuoles; (3) a spore-forming motile rod-shaped bacterium, fermenting sugars, isolated from the Dead Sea; (4) Haloanaerobium praevalens , isolated from the Great Salt Lake, fermenting carbohydrates, peptides, amino acids and pectin to acetate, propionate, butyrate, H₂ and CO₂.
Analysis of their 16S rRNA shows that these organisms are related to each other, but unrelated to any of the other subgroups of the eubacterial kingdom, to which they belong.
Ha. praevalens and Hb. halobius regulate their internal osmotic pressure by the accumulation of salt (Na⁺, K⁺, Cl⁻) rather than by organic osmotic solutes.     

Performance of two Picea abies (L.) Karst. stands at different stages of decline

Summary This is the first in a series of papers on the growth, photosynthetic rate, water and nutrient relations, root distribution and mycorrhizal frequency of two Norway spruce forests at different stages of decline. One of the stands was composed of green trees only while the other included trees ranging in appearance from full green crowns to thin crowns with yellow needles. In this paper we compare the growth and carbohydrate relations of the two stands and examine relationships among growth variables in ten plots. The declining stand produced 65 percent of the wood per ground area compared with the stand in which all trees were green because its foliage produced less wood at any level of leaf area index. The difference in foliage efficiency between the sites could not be explained by differeneces in climate, competition or stand structure. The declining stand appeared to have lower carbon gain as indicated by a smaller increase in reserve carbohydrates before bud break, and weaker sinks for carbohydrates as indicated by less use of the stored carbohydrates than the healthy stand. Thus, growth reduction was probably related to factors which affect both photosynthesis and, even more, the sinks for carbohydrate.     

Why Adult Stem Cell Functionality Declines with Age? Studies from the Fruit Fly Drosophila Melanogaster Model Organism

Highly regenerative adult tissues are supported by rare populations of stem cells that continuously divide to self-renew and generate differentiated progeny. This process is tightly regulated by signals emanating from surrounding cells to fulfill the dynamic demands of the tissue. One of the hallmarks of aging is slow and aberrant tissue regeneration due to deteriorated function of stem and supporting cells. Several Drosophila regenerative tissues are unique in that they provide exact identification of stem and neighboring cells in whole-tissue anatomy. This allows for precise tracking of age-related changes as well as their targeted manipulation within the tissue. In this review we present the stem cell niche of Drosophila testis, ovary and intestine and describe the major changes and phenotypes that occur in the course of aging. Specifically we discuss changes in both intrinsic properties of stem cells and their microenvironment that contribute to the decline in tissue functionality. Understanding these mechanisms in adult Drosophila tissues will likely provide new paradigms in the field of aging.     

Occurrence of oestrogenic pollutants and widespread feminisation of male tilapia in peri-urban dams in Bulawayo,Zimbabwe

Peri-urban water bodies are at risk from excessive pollution as they are direct sinks for urban effluents. The occurrence of oestrogenic and androgenic endocrine disrupting chemicals (EDCs) in effluents and water bodies around the city of Bulawayo, Zimbabwe, and their effects on wild fish was investigated in 2013. Effluent and water were sampled from sewage treatment plants, an urban stream, and effluent-polluted dams, and were compared with a ‘pristine’ dam upstream of Bulawayo. Organic pollutants were extracted by solid-phase extraction and tested for EDCs using a yeast oestrogen/androgen screen. Oestrogenic and androgenic potencies were expressed as 17β-oestradiol equivalent (EEq) or dihydrotestosterone equivalent (TEq). Tilapia and catfish from the dams were analysed for gonado-somatic indices and testis histopathology. Effluents from STPs, which directly flow into Umguza Dam, had EEq of 33 ng l^?1 and 55 ng l^?1, respectively. Umguza Dam, Khami Dam and Matsheumhlope Stream had EEqs of 237 ng l^–1, 9 ng l^?1 and 2 ng l^?1, respectively. Androgenic activity was detected in only one STP (TEq = 93 ng l^?1). Tilapia sampled from effluent-polluted dams had high incidences of testis-ova, but catfish had no signs of reproductive dysfunction. These findings underscore the need for greater attention to EDCs in developing countries where there is scant literature regarding their occurrence and impacts.     

Uptake of water and solutes through twigs of Picea abies (L.) Karst

Summary Uptake of water and magnesium chloride solution was investigated through the outer surface of twigs of Picea abies (L.) Karst. Water uptake was determined by using pressure/volume (P/V) curves of the twigs as a basis for calculation to avoid problems of superficial extraneous water. When water was sprayed on bark and needles of 3- to 7-year-old twigs at a xylem water potential of -1.00 MPa, they absorbed as much as 80 mm³ water in 200 min/g twig dry weight as the twig water potential recovered to -0.15 MPa. With fluorescent dyes, pathways for absorption of water and solutes through the twig bark were found, particularly through the radially orientated ray tissue. In addition to uptake by mass flow, magnesium could also diffuse along a concentration gradient from the twig surface into the xylem. In the field, the magnitude of these uptake processes would depend on the concentration of elements deposited by atmospheric precipitation, the concentration gradient between the plant surface and the xylem sap, the xylem water potential and the intensity and duration of each precipitation event.     

Proteolysis of human C-reactive protein by neutrophil-derived lysosomal enzymes generates peptides which modulate neutrophil function: Implication to the anti-inflammatory mechanism

Summary Proteolysis of human C-reactive protein (CRP) by lysosomal enzymes derived from human neutrophils is shown to yield short peptides capable of modulating the production of superoxide ions by stimulated human neutrophils. Thus, fractionation of trichloroacetic acid-soluble digestion mixtures by HPLC yielded the following peptides: Ser-Tyr (1), Gly-Tyr (2), Phe-Glu-Val-Pro-Glu-Val-Thr (3), Trp-Asp-Phe-Val (4), Asn-Met-Trp-Asp-Phe-Val (5) and Gln-Leu-Trp-Pro (6). These peptides, corresponding to CRP sequences 18–19, 48–49 and/or 72–73, 84–90, 162–165, 160–165 and 203–206, respectively, have been synthesized and peptides 2, 3 and in particular peptide 6 were found to significantly inhibit neutrophilic function. The results suggest that CRP-derived peptides may be capable of regulating superoxide ion production by neutrophils in vivo during the acute phase response as part of a complex protective mechanism.     

Transneuronal Dpr12/DIP‐δ interactions facilitate compartmentalized dopaminergic innervation of Drosophila mushroom body axons

The mechanisms controlling wiring of neuronal networks are not completely understood. The stereotypic architecture of the Drosophila mushroom body (MB) offers a unique system to study circuit assembly. The adult medial MB γ‐lobe is comprised of a long bundle of axons that wire with specific modulatory and output neurons in a tiled manner, defining five distinct zones. We found that the immunoglobulin superfamily protein Dpr12 is cell‐autonomously required in γ‐neurons for their developmental regrowth into the distal γ4/5 zones, where both Dpr12 and its interacting protein, DIP‐δ, are enriched. DIP‐δ functions in a subset of dopaminergic neurons that wire with γ‐neurons within the γ4/5 zone. During metamorphosis, these dopaminergic projections arrive to the γ4/5 zone prior to γ‐axons, suggesting that γ‐axons extend through a prepatterned region. Thus, Dpr12/DIP‐δ transneuronal interaction is required for γ4/5 zone formation. Our study sheds light onto molecular and cellular mechanisms underlying circuit formation within subcellular resolution.     

Down-regulation of wild-type p53 activity interferes with apoptosis of IL-3-dependent hematopoietic cells following IL-3 withdrawal.

Overexpression of wild-type p53 in p53-deficient leukemic cells induces apoptosis, which can be inhibited by hematopoietic survival factors. This suggests that p53 may contribute to survival factor dependence. To assess the role of wild-type p53 in mediating apoptosis following survival factor withdrawal, we interfered with endogenous p53 activity in interleukin-3 (IL-3)-dependent cells. Extended survival without IL-3 was conferred by recombinant retroviruses encoding either a full-length p53 mutant or a C-terminal p53 miniprotein, both of which can act as negative-dominant inhibitors of wild-type p53. On the other hand, excess wild-type p53 activity failed to elicit apoptosis as long as IL-3 was present. We propose that p53 is a positive, though not exclusive, mediator of survival factor dependence in hematopoietic cells.