Biochemical ecology of deep-sea animals.

Deep-sea ecosystems contain unique endemic species whose distributions show strong vertical patterning in the case of pelagic animals and sharp horizontal patterning in the case of benthic animals living in or near the deep-sea hydothermal vents. This review discusses the biochemical adaptations that enable deep-sea animals to exploit diverse deep-sea habitats and that help establish biogeographic patterning in the deep-sea. The abilities of deep-sea animals to tolerate the pressure and temperature conditions of deep-sea habitats are due to pervasive adaptations at the biochemical level: enzymes exhibit reduced perturbation of function by pressure, membranes have fluidities adapted to deep-sea pressures and temperatures, and proteins show enhanced structural stability relative to homologous proteins from cold-adapted shallow-living species. Animals from the warmest habitable regions of hydrothermal vent ecosystems have enzymes and mitochondria adapted to high pressure and relatively high temperatures. The low metabolic rates of bathypelagic fishes correlate with greatly reduced capacities for ATP turnover in locomotory muscle. Reduced light and food availability in bathypelagic regions select for low rates of energy expenditure in locomotory activity. Deep-sea animals thus reflect the importance of biochemical adaptations in establishing species distribution patterns and appropriate rates of metabolic turnover in different ecosystems.     

Sister chromatid exchanges in lymphocytes of normal and alcoholic subjects.

The effects of alcohol consumption, cigarette smoking and age on sister chromatid exchange (SCE) frequency in human lymphocytes were assessed by means of multiple linear regression. An increase in SCE rates was associated with alcohol consumption (p = 0.0001), smoking (p = 0.0231), and, to a small extent (p = 0.057), age. These three confounding factors explain 48% of the inter-personal variation in SCE rates among subjects studied.     

Choleretic and cholestatic effects of infused bile salts in the rat.

In rats, at low infusion rates taurocholate (TC), taurochenodeoxycholate (TCDC) and taurodeoxycholate (TCD) each produced an increase in bile flow of 20-50%. However, at high infusion rates (5-20 mumoles min-1kg-1) the cholestatic effects of the bile salts were revealed and the relative toxicity of the bile salts was seen to be TDC greater than TCDC greater than TC.     

Mitochondrial calcium efflux and porcine stress-susceptibility.

Mitchondrial Ca2+ efflux rates of M. longissimus dorsi correlate very closely with parameters associated with porcine stress-susceptibility. Experimental data support the measurement of mitochondrial Ca+2 efflux to be a very sensitive and reliable method for differentiating porcine stress-susceptibility.     

Hummingbird flight: sustaining the highest mass-specific metabolic rates among vertebrates.

Resting and maximal mass-specific metabolic rates scale inversely with body mass. Small hummingbirds achieve the highest known mass-specific metabolic rates among vertebrate homeotherms. Maximal capacities for O2 and substrate delivery to muscle mitochondria, as well as mitochondrial oxidative capacities in these animals may be at the upper limits of what are structurally and functionally possible given the constraints inherent in vertebrate design. Such constraints on the evolutionary design of functional capacities may play an important role in determining the lower limits to vertebrate homeotherm size and the upper limits to mass-specific metabolic rate.     

Cytokinin ocntents and cAMP metabolism during growth of Escherchia coli.

During Escherichia coli growth, we found an inverse correlation between free cytokinin content and cAMP level. The rates of synthesis of adenylate-cyclase and cAMP-phosphodiesterase were practically constant.     

Alterations of beta-adrenoceptor-density and cAMP-synthesis in rat-erythrocytes after stress erythropoiesis.

During the maturation of red blood cells from rats after stress erythropoiesis, adenyl cyclase activity and beta-adrenoceptor density (pmoles/mg protein) decrease at distinctly different rates suggesting a different turnover of these membrane units.     

Cerebral ammonia production during hypoglycemia in the newborn calf.

The effect of insulin hypoglycaemia on cerebral blood flow, and cerebral metabolic rates of glucose, oxygen and ammonia was investigated in the unanaesthetized newborn calf. A net loss of ammonia from the brain occurred during hypoglycaemia, and was greater in convulsing than in comatose animals.     

Utilization of ascorbic acid during post-embryonic development of chick skeletal muscle.

Ascorbic acid is utilized during the post-embryonic differentiation of skeletal muscle fibres in chick. While the fibres lose their heterogeneity with regard to ascorbic acid, they continue to exhibit differences in their metabolic rates in terms of the succinate dehydrogenase activity throughout life.     

Further evidence of a positive correlation between exposure to nitrate fertilizers (NaNO3 and KNO3) and gastric cancer death rates: nitrites and nitrosamines.

Mean age-adjusted death rates for gastric cancer in Chile for 1960, 1962 and 1964 were associated with exposure to sodium nitrate and nitrates (NaNO3 and KNO3) used as fertilizers, by province. The general population exposure to NaNO3 and nitrates exhibited correlation coefficients of 0.745 and 0.718 with the death rates, respectively.     

Forecast comparisons of four models of U.S. interest rates

In this paper we compare the out of sample forecasts from four alternative interest rate models based on expanding information sets. The random walk model is the most restrictive. The univariate time series model allows for a richer dynamic pattern and more conditioning information on own rates. The multivariate time series model permits a flexible dynamic pattern with own- and cross-series information. Finally, the forecasts from the MPS econometric model depend on the full model structure and information set. In theory, more information is preferred to less. In practice, complicated misspecified models can perform much worse than simple (also probably misspecified) models. For forecasts evaluated over the volatile 1970s the multivariate time series model forecasts are considerably better than those from simpler models which use less conditioning information, as well as forecasts from the MPS model which uses substantially more conditioning information but also imposes ‘structural’ economic restrictions.     

Rheological properties of human blood plasma--a comparison of measurements with three different viscometers.

Human plasma viscosity was measured in capillary tube, cone-plate and Couette viscometers. The measurement of the viscosity at very low shear rates showed that plasma is a non-Newtonian fluid with a pseudoplastic rheological behaviour. The importance of this phenomenon for the microcirculation is discussed.     

A mutant of the antibiotic resistance factor R124 with altered copy number.

A mutation conferring increased antibiotic resistance on Salmonella typhimurium strain 11G carrying R124 was plasmid determined; strains harbouring the mutant plasmid contained more DNA as ccc plasmid than those harbouring R124. The increased copy number was manifested at all growth rates tested.     

Respiratory control in liver mitochondria of rats hosting the walker 256 carcinoma tumor.

The decrease in the respiratory control ratio of mitochondria is a first order process when these organelles are incubated in isotonic sucrose. Furthermore, the initial respiratory control ratios and the rates of loss in respiratory control in liver mitochondria from rats hosting the Walker 256 carcinoma are not significantly different form the same properties of mitochondria from untreated animals.     

Zonulae occludentes in the epidermis of the snakeNatrix natrix L.

Summary Zonulae occludentes of a very tight type were identified between the uppermost stratum germinativum cells of the grass snakeNatrix natrix L. by means of the lanthanum tracer technique. Since zonulae occludentes alone are not capable of preventing transepithelial water flow, an additional barrier mechanism is postulated, responsible for the low rates of cutaneous water loss measured in squamate reptiles. It is suggested that the observed zonulae occludentes are involved in the sloughing process.The skilful technical assistance of Ms E. Weber is gratefully acknowledged.     

Effect of prolactin on fluid and NaCl absorption by the rat proximal and distal colon.

The rates of fluid and NaCl absorption are greater in the proximal than in the distal colon. Prolactin treatment caused significant increases in fluid and NaCl absorption in the proximal but not in the distal colon. This suggests that only the proximal colon region, where most of the fluid and sodium absorption takes place, is responsive to prolactin.     

Practitioners'Forum. Forecasting and Planning the Jeddah Air Traffic with a Mini Model

A simple model of particular socio-economic and technical environment proves useful in forecasting and planning. The specific application forecasts air traffic at King Abdulaziz International Airport (KAIA) in Jeddah, Saudi Arabia, through a number of explanatory variables The purpose of the model is to explain and forecast the change in growth rates of passenger flow through the airport. The dynamics of passenger flow are linked to the dynamics of the oil-based economy of Saudi Arabia and the global economic and business environment.     

A possible age-related decrement in the conduction velocity of Aplysia neuron R2.

In late winter and in spring, the conduction velocity of the R2 axon of Aplysia californica is 0.48 m/sec or more in all specimens. However, in the summer, fall and early winter, some sexually mature animals exhibit markedly diminished R2 conduction rates (as low as 0.24 m/sec). It is possible that this reduced velocity is a reflection of the age of the specimen from which the axon is taken.     

Growth and development of the American bollwormHeliothis armigera Hubn. under laboratory mass rearing conditions

Summary A kidney bean meal diet was the most satisfactory laboratory diet for the larvae of the American bollwormHeliothis armigera Hubn. Optimum rates of survival (63.5%) occurred and the larval growth was better than that of larvae reared on castor oil plant leaves. The pupal weight and the fecundity of the resulting adults were also much better than those on the control host plant.     

Physical growth and brain development of captive-bred male and female squirrel monkeys, Saimiri sciureus.

The physical growth and brain development of the captive bred male and female squirrel monkeys have shown that the male grows at a significantly faster rate with respect to these parameters in the postnatal life, starting from preweaning stage as compared to the female infant. During the prenatal life the male and the female fetuses grow at similar rates and show comparable brain development as indicated by its weight.