Nutritional importance of detritivory in the growth and condition of gizzard shad in an Ohio reservoir

Synopsis Gizzard shad,Dorosoma cepedianum, in Acton Lake, Ohio, ingested foods of varying nutritional quality during the 1981–1983 growing seasons. Adult (ages 2–4) fish fed on a mixed diet (ORG>30%; C:N<7:1) of zooplankton and organic detritus in early summer, and on detrital materials (ORG<16%; C:N>11:1) during the remainder of the growing season. Age 0 (<35 mm standard length) fish ingested only detrital materials. The nutritional quality (ORG = 10 – 20%; C:N<11:1) of these foods displayed little seasonal variation, but was higher than that of organic detritus taken by adult fish in late summer and autumn. Growth and condition of gizzard shad were poor when the diet consisted of detrital materials; however, age 4 fish (1983) grew rapidly and condition improved when zooplankton were consumed. These results suggest that ingestion of poor-quality detritus can reduce the growth and condition of gizzard shad in Acton Lake, whereas the seasonal inclusion of high-quality zooplankton in the diet can result in rapid growth and improved condition.     

Complications of ileal conduit diversion in adults with cancer followed up for at least five years.

A total of 111 adults with malignant disease of the bladder were studied to determine the long term complications of ileal conduit diversion. Each patient had survived at least five years (mean 10 years) after cystectomy. At final follow up the radiological appearance of one or both kidneys had deteriorated in 50 (47%) of 107 patients: deterioration worsened significantly (p less than 0.01) with increasing duration of follow up. Eighteen patients (16%) developed biochemical evidence of impaired renal function, of whom four died of complications of renal failure. Bilateral upper tract dilatation was noted in 30 patients (28%), and in 21 its cause was obscure. Ten patients formed renal stones, and an additional 12 required further operations on the conduit or stoma. Despite the age of patients with bladder cancer and the poor prognosis of those with invasive tumours clinically important side effects were observed in a significant proportion of the long term survivors. Further efforts to determine the aetiology of upper tract dilatation in patients with an ileal conduit diversion are justified.     

Lactate-stimulated ethanol oxidation in isolated hepatocytes

1. Hepatocytes isolated from starved rats and incubated without other substrates oxidized ethanol at a rate of 0.8-0.9mumol/min per g wet wt. of cells. Addition of 10mm-lactate increased this rate 2-fold. 2. Quinolinate (5mm) or tryptophan (1mm) decreased the rate of gluconeogenesis with 10mm-lactate and 8mm-ethanol from 0.39 to 0.04-0.08mumol/min per g wet wt. of cells, but rates of ethanol oxidation were not decreased. From these results it appears that acceleration of ethanol oxidation by lactate is not dependent upon the stimulation of gluconeogenesis and the consequent increased demand for ATP. 3. As another test of the relationship between ethanol oxidation and gluconeogenesis, the initial lactate concentration was varied from 0.5mm to 10mm and pyruvate was added to give an initial [lactate]/[pyruvate] ratio of 10. This substrate combination gave a large stimulation of ethanol oxidation (from 0.8 to 2.6mumol/min per g wet wt. of cells) at low lactate concentrations (0.5-2.0mm), but rates remained nearly constant (2.6-3.0mumol/min per g wet wt. of cells) at higher lactate concentrations (2.0-10mm). 4. In contrast, owing to the presence of ethanol, the rate of glucose synthesis was only slightly increased (from 0.08 to 0.12mumol/min per g wet wt. of cells) between 0.5mm- and 2.0mm-lactate and continued to increase (from 0.12 to 0.65mumol/min per g wet wt. of cells) with lactate concentrations between 2 and 10mm. 5. In the presence of ethanol, O(2) uptake increased with increasing substrate concentration over the entire range. 6. Changes in concentrations of glutamate and 2-oxoglutarate closely paralleled changes in the rate of ethanol oxidation. 7. In isolated hepatocytes, rates of ethanol oxidation are lower than those in vivo apparently because of depletion of malate-aspartate shuttle intermediates during cell preparation. Rates are returned to those observed in vivo by substrates that increase the intracellular concentration of shuttle metabolites.     

Differential inhibition of adenosine deaminase deficient peripheral blood lymphocytes and lymphoid line cells by deoxyadenosine and adenosine.

The response to mitogens of peripheral blood lymphocytes (PBL) from adenosine deaminase deficient (ADA^?) patients with Severe Combined Immunodeficiency (SCID), but not from normals, was more sensitive to inhibition by deoxyadenosine than by adenosine. In contrast, proliferation of long-term lymphoid line (B) cells from these patients was essentially equally inhibited by adenosine and deoxyadenosine. Deoxycytidine could “rescue” ADA^? PBLs from deoxyadenosine toxicity.     

Regeneration of Three <Emphasis Type="Italic">Sphagnum</Emphasis> species

Sphagnum capillifolium var. tenellum, S. magellanicum, and S. recurvum var. brevifolium were regenerated from stem pieces grown in containers to assess their potential for use in peatland restoration projects. The effect of two water levels; peat, peat/sand or peat/clay substrates; and peat decomposition level on the species’ regeneration was evaluated. S. magellanicum attained the greatest cover on the peat or peat/sand mixture using decomposed peat when the growing surface was occasionally inundated. S. recurvum attained the greatest cover grown on the peat or peat/sand mixture using undecomposed peat when the water level was kept below the surface. S. capillifolium showed an affinity for the peat/clay mixture, and overall attained a greater total cover than the other species when grown under the lower water level on all substrate types, with total cover approximately three to five times that of the others. When developing management plans for restoration of mined peatlands, species-specific responses to water level, type and extent of mineral soil mixed with the peat surface, and peat decomposition level should be considered.     

Diet,feeding rate,and assimilation efficiency of American brook lamprey

We examined foods ingested by American brook lamprey larvae from Minnesota streams during spring and summer seasons. The diet was dominated numerically by diatoms, but organic detritus comprised the bulk (>85%) of ingested materials. The organic contents of ingested foods did not differ among streams or between seasons, averaging approximately 70%. Feeding rates based on gut fullness were highest, but most variable, during spring. Assimilation efficiency of the organic fraction of the diet averaged >65% across streams and seasons. Larval American brook lamprey depend on organic detritus to meet most of their nutritional needs and are very efficient at digesting and assimilating these detrital foods. Survival of American brook lamprey populations may be affected by human activities that alter the production and availability of detritus within streams.     

Subfunctionalization of expression and peptide domains following the ancient duplication of the proopiomelanocortin gene in teleost fishes

The proopiomelanocortin gene (POMC) encodes several bioactive peptides, including adrenocorticotropin hormone, alpha-, beta-, and gamma-melanocyte-stimulating hormone, and the opioid peptide beta-endorphin, which play key roles in vertebrate physiology. In the human, mouse, and chicken genomes, there is only one POMC gene. By searching public genome projects, we have found that Tetraodon (Tetraodon nigroviridis), Fugu (Takifugu rubripes), and zebrafish (Danio rerio) possess two POMC genes, which we called POMCalpha and POMCbeta, and we present phylogenetic and mapping evidence that these paralogue genes originated in the whole-genome duplication specific to the teleost lineage over 300 MYA. In addition, we present evidence for two types of subfunction partitioning between the paralogues. First, in situ hybridization experiments indicate that the expression domains of the ancestral POMC gene have been subfunctionalized in Tetraodon, with POMCalpha expressed in the nucleus lateralis tuberis of the hypothalamus, as well as in the rostral pars distalis and pars intermedia (PI) of the pituitary, whereas POMCbeta is expressed in the preoptic area of the brain and weakly in the pituitary PI. Second, POMCbeta genes have a beta-endorphin segment that lacks the consensus opioid signal and seems to be under neutral evolution in tetraodontids, whereas POMCalpha genes possess well-conserved peptide regions. Thus, POMC paralogues have experienced subfunctionalization of both expression and peptide domains during teleost evolution. The study of regulatory regions of fish POMC genes might shed light on the mechanisms of enhancer partitioning between duplicate genes, as well as the roles of POMC-derived peptides in fish physiology.