The role of growth hormone in the regulation of protein metabolism with particular reference to conditions of fasting

Growth hormone (GH) has potent protein anabolic actions, as evidenced by a significant decrease in lean body mass and muscle mass in chronic GH deficiency, and vice versa in patients with acromegaly. Depending on the prevailing physiological conditions and on which tissues and which proteins are under examination, the mechanisms involved include both stimulation of protein synthesis and restriction of protein breakdown. Apart from the possible direct effects of GH on protein dynamics, a number of additional anabolic agents, such as insulin, insulin-like growth factor-I and free fatty acids (FFA), are activated. Some of the most recent studies in the field have demonstrated a decisive role of stimulation of lipolysis and high circulating levels of FFA in orchestrating the maintenance of the protein pool of the body.     

Masticatory ability in 80-year-old subjects and its relation to intake of energy,nutrients and food items

Objective: The aim of the present study was to analyse the relationship between masticatory ability (self‐assessed masticatory ability and bite force) and intake of energy, nutrients and food items in a population sample of elderly subjects. Design and Subjects: From a population sample of 80‐year‐old people, 160 individuals (74 men and 86 women) took part in an odontological study. Main Outcome Measures: A dental examination including bite force recording, a questionnaire focusing on self‐assessed masticatory ability, and a dietary interview. Setting: Department of Geriatric Medicine, Göteborg University, Sweden. Results: The dental status among the participants varied much (from edentulous in both jaws ‐ 22% ‐ to more than 20 natural teeth ‐ 30%). The mean maximum bite force was higher in men (165 N) than in women (105 N). Bite force was significantly correlated to the Eichner index and to the number of teeth. One third of the subjects reported no masticatory problem, whereas 18% identified 3 such problems. The intake of energy and nutrients varied much but the means were well above recommended values. The correlations between dental status and bite force on one side and dietary intake on the other side were in general weak and most often statistically non‐significant. Impaired general health and reduced dentition were both associated with more masticatory problems. Conclusion: The examined sample of 80‐year‐old subjects had a great variation in dental status, bite force and self‐assessed masticatory ability, but these factors had only a minor influence on dietary selection and intake, which on average were well above recommended values.     

Ostracoda and palaeo-oxygen levels, with particular reference to the Upper Cretaceous of East Anglia

It has been shown that the percentage of Platycopina (the sole remaining group of filter-feeding Ostracoda since the global extinction of the Metacopina in the Lower Toarcian) making up a fossil ostracod fauna can be used as a measure of dissolved oxygen in past oceans. High levels of platycopids indicate low oxygen and vice versa. A new scale is introduced here, based mainly on the environmental oxygen levels of modern oceans and their equivalent percentages of living platycopids, in order to evaluate the palaeo-oxygen levels of the Upper Chalk in East Anglia. The effects of varying oxygen concentrations on the overall simple species diversity of the Ostracoda is also shown to have important palaeoenvironmental implications. The study is based on 79 samples from the Santonian to Lower Maastrichtian of the Trunch Borehole and 126 samples from outcrops in Suffolk and Norfolk, ranging from the Coniacian to Lower Maastrichtian. The Coniacian is shown to have been a time of low to very low oxygen, except for its upper part that was much better ventilated. The Santonian and Lower Campanian were low to very low in their dissolved oxygen, while the Upper Campanian and particularly the Lower Maastrichtian had much higher oxygen levels. Notwithstanding these general trends, oxygen levels appear to have fluctuated rapidly throughout the interval, during times of both generally low and high oxygenation. These variations in oxygenation are thought to have been associated with the Oxygen Minimum Zone and its migrations onto the continental shelf and subsequent retreat to the continental slope. This in turn is related to sea-level fluctuations and this, together with the potential for the application of this technique to sequence stratigraphy are discussed.     

The colour change of the minnow, Phoxinus phoxinus with particular reference to the effect of spinal lesions

An account is given of the anatomy of the spinal cord of the minnow, Phoxinus phoxinus L., and comparisons are made with the spinal cords of other teleosts. The effects on the rapid, neurally controlled colour responses of complete transection of the spinal cord at different levels indicated that, in the particular fish used for this work, the sympathetic pigmento-motor fibres had a localized outflow from the spinal cord around vertebra 13. Partial lesions of the spinal cord at vertebrae 3, 4, 10 and 11 and their effects on the colour responses indicated that, at these spinal levels, the pigmento-motor fibres were dorsomedially located within the dorsal horns. Complete and partial transection of the spinal cord at any single level between vertebrae 12 and 14 and partial transection of the dorsomedial spinal tissues at vertebrae 3, 4, 10 and 11 resulted in differential paling of the entire dorsolateral skin of the fish in response to a change of background from black to white. It would appear that in both cases this differential response of the melanophores was the result of transecting a proportion of the spinal pigmento-motor fibres.     

不同温度下黑线仓鼠应对食物短缺的能量学对策

食物资源的不确定性是动物在自然环境中面临的重要挑战之一."代谢率转换"假说认为,动物应对食物短缺的能量学策略在于降低代谢率以减少能量支出.然而在不同环境温度下非冬眠小型哺乳动物应对食物短缺的"代谢率转换"策略,尚不明确.为探究这一问题,将成年雄性黑线仓鼠在低温(5.0℃)、室温(21.0℃)和高温(32.5℃)下断食处...     

A taxonomic study of thePoa macrocalyx complex,with particular reference to the populations in eastern Hokkaido

An attempt was made to investigate some populations of thePoa macrocalyx complex in eastern Hokkaido in relation to the taxonomy of this complex. Individual specimens preserved in TI, KYO and TNS were also studied. Chromosome counts of 2n=42 were obtained in the majority of a total of 84 collections, and counts of 2n=63 (incl. ca. 63), ca. 70 and 84 were also made in a few collections. High percentages of viable pollen were observed. The morphological features which were designated by previous authors to be significant in separatingPoa sachalinensis fromP. macrocalyx and in discriminating between the varieties ofP. macrocalyx were critically examined with emphasis on the observations of infra-population variation. It was confirmed that (1) the populations of thePoa macrocalyx complex in eastern Hokkaido are greatly variable morphologically and are also in a dynamic state cytogenetically, (2) plants of this complex in eastern Hokkaido belong to one and the same species,P. macrocalyx, and the varietiesfallax, scabriflora andtatewakiana may be merely morphs, and (3) some plants which are somewhat different from the plants in eastern Hokkaido with respect to glume features are distributed in Sakhalin, and northern and central Hokkaido. Some problems which should be subjected to further studies are pointed out.     

The levels of metals in dock-yard sediments with particular reference to the contributions from ship-bottom paints

Levels of the metals copper, lead, tin and zinc have been determined in a range of shipbottom paints by atomic absorption spectrophotometry. Copper, lead and zinc have been similarly determined in concentrated nitric acid digests and 1M ammonium acetate extracts of sediments taken from enclosed dock-basins at Liverpool, Tilbury and Manchester.At each of the dock-yards concentrations of all the metals in nitric acid extracts were elevated in the vicinity of dry-docks. These elevations are believed to be due to the presence of residues from the ship-bottom paints. The amounts of copper and zinc, which are major components of antifoulant paints, in the ammonium acetate extracts correlate closely with the levels in the nitric acid digests; lead, which is found mainly in anticorrosive and primer paints, does not.Direct toxic effects of the metals to marine organisms are considered, but are not thought to be important in view of the large dilution and dispersed capacities usually available. The possibility of organisms developing genetic resistance to heavy metals in enclosed dock-basins is discussed. It is noted that many of the dock-yard organisms are components of the ship-fouling ecosystem, so that the premature exposure to the toxins of antifoulant paints may result in the development of toxin resistance of considerable economic importance.     

Effect of transection at different levels of hypothalamus on the hypothalamo-hypophysial system of the toad,Bufo bufo,with particular reference to the ultrastructure of the zona externa of the median eminence

Summary The ultrastructural changes taking place in the median eminence of Bufo bufo 3 hours to 4 months after transection of the brain at different levels, are described.5 types of neurons in the zona externa of the median eminence of normal toads are described. All types of neurons degenerate, and profound changes of the ultrastructure of the capillaries are observed after transection just behind, or immediately in front of the optic chiasma. A few neurons containing dense granules with a diameter of about 1,000–1,300 Å remain intact, however. The degeneration following denervation in front of the optic chiasma was considerably delayed compared to degeneration after denervation behind the optic chiasma.After transection more rostral to the optic chiasma, no significant degeneration of the median eminence was observed.The results are discussed with regard to degenerative dynamics and origin of the different nerve types. It is concluded, that all types of neurons terminating in the median eminence, originate at a level between the caudal and rostral parts of the preoptic nucleus, some fibres, however, containing dense, 1,000–1,300 Å granules, originate caudally to the optic chiasma, in the posterior hypothalamus.Part of this study was presented at the Vth International Symposium on Neurosecretion, Kiel, Germany, August 1969.     

The biology of terns nesting at Aldabra Atoll, Indian Ocean, with particular reference to breeding seasonality

Five species of tern breed on Aldabra Atoll (09° 24' S; 46° 20' E). The Caspian tern Sterna caspia and Crested tern S. bergii feed exclusively in very shallow reef/lagoon water, the Fairy tern Gygis alba and Brown noddy Anous stolidus feed out at sea, and the Black-naped tern Sterna sumatrana is intermediate in its foraging. Both of the shallow-water species lay during the south-east monsoon season, the Caspian tern from April to August and the Crested tern from June to August, but the Crested tern also lays in December and January. The remaining three species have extended laying periods largely circumscribed by the north-west monsoon season from November to March. Breeding population size of the Caspian tern is in the low tens and of the Brown noddy in the low thousands, with the other species each numbering in the hundreds. The distribution and abundance of the nine species of tern breeding within the Seychelles ( sensu lato ) vary on the different island groups in a manner interpretable in terms of depth of the surrounding waters. Systematic differences between the central Seychelles and Aldabra groups in timing of breeding by terns which feed out at sea may be associated with seasonal latitudinal movement of the divergence zone between the South Equatorial Current and the Equatorial Counter-current, acting via correlated latitudinal shifts of prey species and game-fish abundance.     

Lipid globules at the midpieces of Glyptocidaris crenularis spermatozoa and their relation to energy metabolism

Spermatozoa of the sea urchin, Glyptocidaris crenularis, use endogenous triglycerides (TG), not phosphatidylcholine, to produce energy for swimming. This study was undertaken to examine ultrastructurally the location of TG available for utilization in energy metabolism in these spermatozoa. Each spermatozoon contained several lipid globules at the bottom of the midpiece. Following incubation with sea water, both the number and size of the lipid globules decreased significantly. The total volume of lipid globules in each spermatozoon was roughly halved after 1 h of incubation. Similarly, about half of the TG was metabolized during the same incubation period. Oxygen consumption by spermatozoa during the incubation indicated the oxidation of fatty acid derived from TG. Thus it appears that G. crenularis spermatozoa obtain energy through oxidation of fatty acid from TG stored in the lipid globules within their midpieces. © 1993 Wiley-Liss, Inc.