OPTIMIZATION OF THE ENUMERATION OF TOTAL AEROBIC BACTERIAL FLORA IN THE FLESH OF SEAFISH

Abstract The total aerobic flora of seafish flesh is weakly halophilic, and requires on average 1.38% NaCl according to statistical studies. Enumeration is optimal on tryptone soya agar or on NaCl supplemented plate count agar (-H₂S), incubated at 20 and 25C, respectively. Plate count agar (-H₂S) was selected because it can also be used for enumeration of hydrogen sulfide-producing bacteria by degradation of sulfur-containing proteins, which are abundant in fish The models employed are sigmoidal. The initial bioburden is too great for there to be a lag phase during storage in ice at 0C. The models show that when the total aerobic microflora count exceeds 100,000 cfu/g, whole or filleted fish stored on ice at 0C are unfit for consumption.     

Factors affecting depth distribution of dragonflies and other benthic insects in a thermally destabilized reservoir

The distribution and abundance of macroinvertebrates along a water depth gradient were studied in thermal and ambient temperature areas of a reservoir in the southeastern United States. Benthic samples were taken at 10 depths (0.16–5 m) during January–April, 1978. Factors affecting the depth distribution of Ceratopogonidae, Chaoboridae, Chironomidae, Ephemeroptera, Odonata, and Trichoptera are discussed. The relationship between abundance of organisms and water depth was more complex than an inverse relationship generally reported in the literature.     

Efferocytosis Fuels Requirements of Fatty Acid Oxidation and the Electron Transport Chain to Polarize Macrophages for Tissue Repair

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Stable isotope evidence for impala Aepyceros melampus diets at Akagera National Park,Rwanda

Stable isotope analysis of tooth enamel was used to investigate the relative proportions of grass and browse in seasonal and overall diets of impala Aepyceros melampus at Akagera National Park, Rwanda. Bulk enamel samples suggest that on average, impala ate c. 86% C₄ grass year‐round, far more than in most previously studied impala populations across Africa. Intra‐tooth samples show that seasonal changes in the proportion of C₄ grass versus C₃ browse are minimal (c. 10%), the diet being dominated by C₄ grass year‐round in contrast to other impala populations that consume ≥50% browse during the dry season. Intra‐tooth oxygen isotope values track carbon isotope changes to a moderate degree, but are not patterned clearly enough to permit identification of wet versus dry seasons. As other studies have shown that impala select high‐protein diets, the foraging behaviour at Akagera is probably because of the availability of palatable grass for much of the year in the edaphic grasslands around the lacustrine environments of the eastern portions of Akagera National Park.     

Flexibility of ephemeral wetland crustaceans: environmental constraints and anthropogenic impacts

Ephemeral wetlands commonly experience events that would be drastic disturbances in permanent aquatic ecosystems, such as the elimination of all water. It is well known that survival in these harsh habitats requires flexibility in response to natural perturbations, but scientists have rarely investigated if this flexibility translates to anthropogenic stresses. Therefore, we evaluated aquatic crustacean communities in ephemeral wetlands in response to environmental and anthropogenic constraints. We sampled crustacean communities from 73 ephemeral wetlands across 5 states of the North American high plains. Neither habitat size, habitat depth, nor whether a wetland was natural or artificially created had any recognizable effect on the crustacean community. Moreover, natural communities have great flexibility, which seems to impart resilience under some anthropogenic forces. Communities of artificial waterbodies (roadside ditches and stock ponds) were indistinguishable from those in naturally formed wetlands. Cattle grazing, which in some ways resembles effects of native vertebrate grazers, was generally associated with increased invertebrate densities and richness. In contrast, tilling for row-crop agriculture decreased invertebrate density and richness. Overall, current conservation strategies in ephemeral wetlands may need to be revised to include artificial habitats as viable, important habitats, and cattle grazing as an essential ecosystem component in areas now lacking large native grazers, such as bison.     

Effect of graded fructose coingestion with maltodextrin on exogenous 14C-fructose and 13C-glucose oxidation efficiency and high-intensity cycling performance.

The ingestion of solutions containing carbohydrates with different intestinal transport mechanisms (e.g., fructose and glucose) produce greater carbohydrate and water absorption compared with single-carbohydrate solutions. However, the fructose-ingestion rate that results in the most efficient use of exogenous carbohydrate when glucose is ingested below absorption-oxidation saturation rates is unknown. Ten cyclists rode 2 h at 50% of peak power then performed 10 maximal sprints while ingesting solutions containing (13)C-maltodextrin at 0.6 g/min combined with (14)C-fructose at 0.0 (No-Fructose), 0.3 (Low-Fructose), 0.5 (Medium-Fructose), or 0.7 (High-Fructose) g/min, giving fructose:maltodextrin ratios of 0.5, 0. 8, and 1.2. Mean (percent coefficient of variation) exogenous-fructose oxidation rates during the 2-h rides were 0.18 (19), 0.27 (27), 0.36 (27) g/min in Low-Fructose, Medium-Fructose, and High-Fructose, respectively, with oxidation efficiencies (=oxidation/ingestion rate) of 62-52%. Exogenous-glucose oxidation was highest in Medium-Fructose at 0.57 (28) g/min (98% efficiency) compared with 0.54 (28), 0.48 (29), and 0.49 (19) in Low-Fructose, High-Fructose, No-Fructose, respectively; relative to No-Fructose, only the substantial 16% increase (95% confidence limits +/-16%) in Medium-Fructose was clear. Total exogenous-carbohydrate oxidation was highest in Medium-Fructose at 0.84 (26) g/min. Although the effect of fructose quantity on overall sprint power was unclear, the metabolic responses were associated with lower perceptions of muscle tiredness and physical exertion, and attenuated fatigue (power slope) in the Medium-Fructose and High-Fructose conditions. With the present solutions, low-medium fructose-ingestion rates produced the most efficient use of exogenous carbohydrate, but fatigue and the perception of exercise stress and nausea are reduced with moderate-high fructose doses.     

Toll‐like receptor‐mediated IRE1α activation as a therapeutic target for inflammatory arthritis

In rheumatoid arthritis (RA), macrophage is one of the major sources of inflammatory mediators. Macrophages produce inflammatory cytokines through toll‐like receptor (TLR)‐mediated signalling during RA. Herein, we studied macrophages from the synovial fluid of RA patients and observed a significant increase in activation of inositol‐requiring enzyme 1α (IRE1α), a primary unfolded protein response (UPR) transducer. Myeloid‐specific deletion of the IRE1α gene protected mice from inflammatory arthritis, and treatment with the IRE1α‐specific inhibitor 4U8C attenuated joint inflammation in mice. IRE1α was required for optimal production of pro‐inflammatory cytokines as evidenced by impaired TLR‐induced cytokine production in IRE1α‐null macrophages and neutrophils. Further analyses demonstrated that tumour necrosis factor (TNF) receptor‐associated factor 6 (TRAF6) plays a key role in TLR‐mediated IRE1α activation by catalysing IRE1α ubiquitination and blocking the recruitment of protein phosphatase 2A (PP2A), a phosphatase that inhibits IRE1α phosphorylation. In summary, we discovered a novel regulatory axis through TRAF6‐mediated IRE1α ubiquitination in regulating TLR‐induced IRE1α activation in pro‐inflammatory cytokine production, and demonstrated that IRE1α is a potential therapeutic target for inflammatory arthritis.     

Opercular regeneration in Pomatoceros lamarckii Quatrefages (Polychaeta: Serpulidae). Differentiation of the operculum and deposition of the calcareous opercular plate

Following opercular amputation, stages in opercular regeneration in Pomatoceros lamarckii have been described by light, transmission and scanning electron microscopy. Two to three days after amputation, the rudimentary opercular filament is invested with a delicate cuticle composed of an outer filamentous layer and an inner thicker component composed of orthogonally-arranged layers of small fibril bundles. The opercular plate is uncalcified and composed of two major components, an outer, thin, electron-dense layer and an inner, thicker component which structurally resembles that of the opercular filament cuticle. Between five and eight days, opercular plate calcification is initiated as needle-like crystallites. The structural organization of the organic components of the opercular plate show changes which are related to the onset of calcification. From 13–17 days, the opercular plate becomes heavily calcified and is composed of highly-ordered, prism-like crystals. X-ray diffraction shows these crystals to be aragonite. The structure of the cuticle remains unchanged except that the orthogonally-arranged fibril bundles aggregate into thicker fibres. Amino acid analysis of the regenerated cuticle and organic components of the opercular plate show that they differ from one another and from the normal cuticle and opercular plate. During opercular regeneration, the differentiation of the cuticle and opercular plate-secreting cells are described and the mechanisms of cuticle and calcareous opercular plate secretion are discussed.