Changes in gill histology of fathead minnows and yellow perch transferred to soft water or acidified soft water with particular reference to chloride cells

Summary Fathead minnows, Pimephales promelas, and yellow perch, Perca flavescens, were transferred from moderately soft Lake Superior water (hardness 45mg/l as CaCO₃) to very soft diluted Lake Superior water (hardness 4.5mg/l). Sulfuric acid was added in some treatments by means of a multichannel diluter. In very soft water, chloride cells proliferated in the gills, especially in the epithelium of the secondary lamellae. When exposed to acid, chloride cells were damaged and less abundant in the secondary lamellae, and blood osmolality was reduced at pH 5.0 (x = 188 mOsm/kg, 9 days exposure; normal 280 mOsm/kg) for the minnows and pH 4.1 (x = 218 mOsm/kg, 58 days exposure; normal 329 mOsm/kg) for the perch. Certain chloride cells which form gland-like clusters in the primary lamellae of perch gills showed little damage even at pH 4.1. The present study supports the view that chloride cells proliferate in very soft fresh water to help maintain ionic balances, and that damage to these cells in acidified soft water may be related to diminished ionoregulatory capacity. The greater acid tolerance of chloride cells of, and the higher blood osmolality maintained by, perch could help to explain the greater tolerance of this species to low pH. In some cases, a species' ability to acclimate to very soft water and acidified soft water may depend upon the number, distribution, and physiology of its chloride cells.     

Evolutionary relationship between Enterobacteriaceae: comparison of the ATP synthases (F1F0) of Escherichia coli and Klebsiella pneumoniae

The ATP synthase complex of Klebsiella pneumoniae (KF₁F₀) has been purified and characterized. SDS-gel electrophoresis of the purified F₁F₀ complexes revealed an identical subunit pattern for E. coli (EF₁F₀) and K. pneumoniae. Antibodies raised against EF₁ complex and purified EF₀ subunits recognized the corresponding polypeptides of EF₁F₀ and KF₁F₀ in immunoblot analysis. Protease digestion of the individual subunits generated an identical cleavage pattern for subunits , , , , a, and c of both enzymes. Only for subunit different cleavage products were obtained. The isolated subunit c of both organisms showed only a slight deviation in the amino acid composition. These data suggest that extensive homologies exist in primary and secondary structure of both ATP synthase complexes reflecting a close phylogenetic relationship between the two enterobacteric tribes.Abbreviations ACMA 9-amino-6-chloro-2-methoxyacridine - DCCD N,N-dicyclohexylcarbodiimide - FITC fluorescein isothiocyanate - SDS sodium dodecyl sulfate - TTFB 4,5,6,7-tetrachloro-2-trifluoromethylbenzimidazole     

Influence of cold exposure on blood lactate response during incremental exercise

This study examined the effect of acute exposure of the whole body to cold on blood lactate response during incremental exercise. Eight subjects were tested with a cycle ergometer in a climatic chamber, room temperature being controlled either at 24 degrees C (MT) or at -2 degrees C (CT). The protocol consisted of a step increment in exercise intensity of 30 W every 2 min until exhaustion. Oxygen consumption (VO2) was measured at rest and during the last minute of each exercise intensity. Blood samples were collected at rest and at exhaustion for estimations of plasma norepinephrine (NE), epinephrine (E), free fatty acid (FFA) and glucose concentrations, during the last 15 s of each exercise step and also during the 1st, 4th, 7th, and the 10th min following exercise for the determination of blood lactate (LA) concentration. The VO2 was higher during CT than during MT at rest and during nearly every exercise intensity. At CT, lactate anaerobic threshold (LAT), determined from a marked increase of LA above resting level, increased significantly by 49% expressed as absolute VO2, and 27% expressed as exercise intensity as compared with MT. The LA tended to be higher for light exercise intensities and lower for heavy exercise intensities during CT than during MT. The E and NE concentrations increased during exercise, regardless of ambient temperature. Furthermore, at rest and at exhaustion E concentrations did not differ between both conditions, while NE concentrations were greater during CT than during MT. Moreover, an increase off FFA was found only during CT.(ABSTRACT TRUNCATED AT 250 WORDS)     

Adrenergic nerves and 5-hydroxytryptamine-containing cells in the pulmonary vasculature of the aquatic file snake Acrochordus granulatus

Summary The adrenergic innervation of the pulmonary vasculature of the file snake Acrochordus granulatus was examined by use of glyoxylic acid-induced fluorescence. Perivascular plexuses of blue-green fluorescent nerves are observed around the common pulmonary artery, the anterior and posterior pulmonary arteries, the arterioles leading to the gas exchange capillaries of the lung, the venules draining the lung, and the anterior and posterior pulmonary veins. Adrenergic nerves are also associated with the visceral smooth muscle of the lung septa and other tissues. Thus, adrenergic control of pulmonary blood flow may occur either at the common pulmonary artery or more regionally within the lung. Regional control of blood flow in the elongate lung of this snake may be important in matching pulmonary perfusion with the distribution of respiratory gas. Glyoxylic acid-histochemistry and immunohistochemistry revealed that populations of cells located in the common pulmonary artery contain the indoleamine 5-hydroxy-tryptamine. Many of the cells are intimately associated with varicose blue-green fluorescent nerves. It is proposed that the 5-hydroxytryptamine-containing cells may be involved in intravascular chemoreception.     

Algesia and local responses induced by neurokinin A and substance P in human skin and temporal muscle

Neurokinin A (NKA), substance P (SP) and the two peptides combined (SP + NKA) were injected intracutaneously on the forearm and into the temporal muscle of healthy volunteers. Pain intensity, cutaneous wheal and flare responses and tenderness of the temporal muscle were quantitated. SP but not NKA induced cutaneous pain. This relates the algesic effect of SP to the specific N-terminal amino acid sequence of the peptide, not shared by NKA. NKA, however, potentiated the algesic effect of SP as SP + NKA induced a significantly prolonged cutaneous pain sensation. Both peptides induced wheals, but only SP induced flare. These results confirm previous studies relating wheal formation to the identical C-terminal amino acid sequence of the two peptides and flare reaction to the N-terminal part of SP. Injections into the temporal muscle did not cause pain or tenderness.     

Appearance of B and H blood group antigens in the developing cochlear hair cells

Summary The presence of human blood-group antigens was analyzed in the rat cochlea during its postnatal development, using anti-A, anti-B and anti-H antibodies. At no stage was reactivity with anti-A antibody observed. With the anti-H antibody, a strong reactivity was observed from 1 to 9 days after birth within hair cells and some other surface epithelial cells of the cochlear duct. After postnatal day 9, only a faint reactivity persisted in a few non-sensory cells. With the anti-B antibody, only hair cells were selectively labeled. At early stages (postnatal day 1 and 3), the reactivity was intense and observed both around the cell surface and within the supranuclear region of cytoplasm. Later on, the reactivity decreased; it was limited at postnatal day 9 to a reactive spot below the cuticular plate. Results are compared with a preliminary finding describing the first appearance of B and H antigens in the organ of Corti at a prenatal stage, and with data concerning other sensory and neural structures. The appearance and progressive disappearance of B and H antigens on sensory and non-sensory cells can be correlated with significant events in the development of the cochlea. The transient expression of B and H antigens in cochlear sensory cells may correspond to developmental changes in their surface glycoconjugates.     

Effect of alcohol on perceived exertion in relation to heart rate and blood lactate

The purpose of the study was to determine whether the perception of exertion is affected by alcohol during physical performance and whether altered self-rating of exertion is the result of an altered perception per se or of an altered physical capacity to perform work. Ten healthy men participated. Each subject was his own control and received an alcohol dose corresponding to 1 g.kg-1 body mass in 40% solution in the experimental session. The exercise test was performed on a cycle ergometer with an initial intensity of 50 W which was increased stepwise by 50 W at 4-min intervals up to near-maximal. The rating of perceived exertion (RPE) did not differ between alcohol and control sessions. Alcohol induced a significant increase in heart rate during exercise at 50 W (delta x = 8 beats.min-1) and at 100 W (delta x = 10 beats.min-1), while the change at higher intensities was insignificant. The systolic blood pressure and the blood lactate concentration were not significantly changed by alcohol. It is concluded that a moderate dose of alcohol does not alter RPE during physical exercise either per se or secondarily to an altered physical capacity to perform work.     

Somatic characteristics of an Australian population of Oreochromis mossambicus (Pisces: Cichlidae)

Synopsis The Oreochromis mossambicus population of North Pine Dam, Brisbane, Queensland, Australia was studied over three years, from 1985 to 1988. Basic somatic data were obtained and characteristic values of condition factor, sex ratio, gonosomatic index and the relationships between total and standard lengths, and length and weight, were calculated. Standard length is proportional to total length by the formula SL = –0.321 + 0.799 TL. Weight is related to length by the isometric formula W = aL³. Condition factor values spanned the range 0.0254 to 0.0563, with an average of 0.04078 for males and 0.03877 for females. The sex ratio is 1: 1 until maturity is reached (21 cm SL), at which time the catch rate of the sexes varies due to divergent habitat selection behaviour. Average values of gonosomatic index, considered in relation to maturity classification, are similar to those obtained from other populations, however maximum values are generally much lower, at 0.47 for males and 3.62 for females. These characteristic values are compared, with varying degrees of concordance, with those for populations of this species in other countries.     

一个描述多种产量-密度关系的经验模型

本文提出一个新的关于产量-密度关系的经验模型,该模型具有以下主要特点。(1) 能描述低密度下不存在种内干扰的产量-密度的直线关系;(2) 能描述从直线型、渐近无极限型、渐近极限型到变型抛物型等多种产量密度类型;(3)参数具有显著的生态学意义。 对温室和田间试验中种内干扰与产量密度关系的实例研究结果表明,该模型能很好地描述在不同程度的种内干扰下所产生的多种类型的产量-密度关系。     

Effects of training at simulated altitude on performance and muscle metabolic capacity in competitive road cyclists

Differences between the effects of training at sea level and at simulated altitude on performance and muscle structural and biochemical properties were investigated in 8 competitive cyclists who trained for 3-4 weeks, 4-5 sessions/week, each session consisting of cycling for 60-90 min continuously and 45-60 min intermittently. Four subjects, the altitude group (AG), trained in a hypobaric chamber (574 torr = 2300 m above sea level), and the other four at sea level (SLG). Before and after training work capacity was tested both at simulated altitude (574 torr) and at sea level, by an incremental cycle ergometer test until exhaustion. Work capacity was expressed as total amount of work performed. Venous blood samples were taken during the tests. Leg muscle biopsies were taken at rest before and after the training period. AG exhibited an increase of 33% in both sea level and altitude performance, while SLG increased 22% at sea level and 14% at altitude. Blood lactate concentration at a given submaximal load at altitude was significantly more reduced by training in AG than SLG. Muscle phosphofructokinase (PFK) activity decreased with training in AG but increased in SLG. All AG subjects showed increases in capillary density. In conclusion, work capacity at altitude was increased more by training at altitude than at sea level. Work capacity at sea level was at least as much improved by altitude as by sea level training. The improved work capacity by training at altitude was paralleled by decreased exercise blood lactate concentration, increased capillarization and decreased glycolytic capacity in leg muscle.