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1.
John P. Dittami 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1986,156(5):641-647
Summary Populations of Reichenow's weavers and rufous sparrows living at the equator were investigated and compared for seasonality in breeding, moulting and fluctuations in the plasma titers of LH, testosterone (in males) and estradiol (in females). These species did not breed during the dry season and they commenced breeding at the onset of the heavy rains (April). In both species, the change from the dry season to the rainy season was accompanied by dramatic increases in gonadal size and steroidogenesis. Surprisingly, plasma titers of the hypophysial hormone LH were not affected.Differences were found in the length of the breeding season: in the weavers it was terminated in September whereas the sparrows bred through January, the end of the study. The differences between the two species in the absence of a pronounced dry season are assumed to be related to the sparrow's ability to interrupt moult and renest in fall when environmental conditions are favourable. in the weavers, no differences in the seasonal changes in gonadal size and plasma titers of LH, T (males) and E2 (females) were found between wet and dry post-heavy rain periods (October–January) whereas differences were found in the sparrows.Abbreviations
E2
estradiol
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T
testosterone
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LH
luteinizing hormone 相似文献
2.
E. Gwinner G. Gänshirt J. Dittami 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1989,165(1):35-39
Summary In the European starling,Sturnus vulgaris, circannual rhythms in gonadal size, molt and other related functions persist only in photoperiods close to 12 h, but are absent in longer or shorter daylengths. To find out whether the arrhythmia seen in long photoperiods results from an arrest of the underlying clock system, three groups of male starlings were held for 10, 14, or 20 months in a 13 h photoperiod and then transferred to a 12 h photoperiod. A control group was held in the 13 h photoperiod throughout the experiment for 28 months. During the initial exposure to the 13 h photoperiod, all birds went through a gonadal cycle, followed by a complete molt. Subsequently, the control birds retained small testes to the end of the experiment and there was no further molt. In contrast, most of the experimental birds re-initiated a testicular cycle, following transfer to the 12 h photoperiod and molted after its completion. The latency between the transfer to the 12 h photoperiod and the onset of testicular growth was not significantly different among the three groups, indicating that the underlying circannual clock had been arrested in the 13 h photoperiod and restarted in the 12 h photoperiod. The pattern of the second testicular cycle did, however, differ among groups. Particularly its amplitude decreased from group 1 to group 3, suggesting that the capacity of the birds to respond to a 12 h photoperiod decreased with increasing duration of exposure to the 13 h photoperiod.Dedicated to Prof. Dr. C.S. Pittendrigh on the occasion of his seventieth birthday. 相似文献
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Janaka?WeragodaEmail author Rohini?Seneviratne Manuj?C.?Weerasinghe SM?Wijeyaratne 《BMC research notes》2016,9(1):508
Background
Peripheral artery disease (PAD) is an important global health problem and contributes to notable proportion of morbidity and mortality. This particular manifestation of systemic atherosclerosis is largely under diagnosed and undertreated. For sustainable preventive strategies in a country, it is mandatory to identify country-specific risk factors. We intended to assess the risk factors of PAD among adults aged 40–74 years.Methods
This case control study was conducted in 2012–2013 in Sri Lanka. Seventy-nine cases and 158 controls in the age group of 40–74 years were selected for the study in order to have case to control ratio 1:2. The criterion for selecting cases and control was based on Ankle brachial pressure index (ABPI). Cases were selected from those who had ABPI 0.85 or less (ABPI ≤0.85) in either lower limb. Controls were selected from those ABPI score between 1.18 and 1.28 in both lower limbs. Only newly identified individuals with PAD were selected as cases. Controls were selected from the same geographical location and within the 5 year age group as cases.Results
The history of diabetes mellitus more than 10 years (OR 5.8, 95% CI 2.2–14.2), history of dyslipidemia for more than 10 years (OR 4.9, 95% CI 2.1–16.2), history of hypertension for more than 10 years (OR 3.8, 95% CI 1.8–12.7) and smoking (OR 2.9, 95% CI 1.2–6.9), elevated HsCRP (OR 3.7, 95% CI 1.2–12.0) and hyperhomocysteinemia (OR 3.0, 95% CI 1.1–8.1) were revealed as country specific significant risk factor of PAD.Conclusions
Diabetes mellitus, hypertension, dyslipidemia, smoking as well as elevated homocysteine and HsCRP found as risk factors of PAD. Longer the duration or higher level exposure to these risk factors has increased the risk of PAD. These findings emphasis the need for routine screening of PAD among patients with the identified risk factors.5.
AP Shoko SM Limbu HA Lamtane MA Kishe-Machumu B Sekadende EE Ulotu 《African Journal of Aquatic Science》2019,44(1):15-24
Aquaculture practices from sub-Saharan Africa are characterised by low production, owing to improper technology. Production can be increased through integrating fish farming with other existing on-farm activities, particularly livestock husbandry. We assessed the role of fish-poultry integration on all male Nile tilapia, Oreochromis niloticus growth performance, yields and economic benefits among smallholder farmers in sub-Saharan Africa, Tanzania. The study also compared phytoplankton species composition, abundance and biomass between the fish-poultry integration and non-integrated system. After 180 days of the experiment, all male O. niloticus cultured under fish-poultry integration exhibited significantly higher growth rates than those in the non-integrated system (p < 0.05). Gross fish yield (GFY), net fish yield (NFY) and net annual yields (NAY) obtained from fish-poultry integration were significantly higher than those from non-integrated system (p < 0.05). Partial enterprise budget analysis revealed that fish-poultry integration was more profitable than the non-integrated system. Moreover, fish-poultry integrated system produced significantly higher phytoplankton abundance and biomass than those from the non-integrated system. Results demonstrate that rural smallholder farmers can achieve higher growth rate, farm net yields and income by integrating all male O. niloticus with other on-farm activities than practising a stand-alone fish culture system. 相似文献
6.
Didone?FrigerioEmail author Katharina?Hirschenhauser Erich?M?stl John?Dittami Kurt?Kotrschal 《Acta ethologica》2004,7(1):9-18
Testosterone modulates male vertebrates sexual and social behaviour. We experimentally investigated the testosterone-sensitive behaviours in male greylag geese (Anser anser) by implanting silastic tubes containing crystalline testosterone during the mating season (February; 5 implanted and 5 control males) and in the early winter (November; 7 and 7). Focal animals were part of a semi-tame, unrestrained flock with fully intact social relationships. Excreted testosterone and corticosterone immunoreactive metabolites (TM, BM) were determined by enzyme immunoassay. Individual faecal samples and behavioural protocols were collected daily over a period of 5 weeks, including 1 control week before implantation. In February, no significant behavioural effects of the supplemental testosterone were observed, which may be due to the naturally occurring high systemic androgen levels in spring. In November, however, implanted males had higher TM excretion rates and performed status signalling behaviour (beak up) more frequently than control males. No differences between implanted and control males were found with respect to BM, agonistic interactions or vigilance behaviour. Furthermore, during the second week after implantation, TM positively correlated with the frequency of beak up of implanted males, whilst their female partners were attacked with lower latency by other members of the flock than the females of control males. Hence, status signalling in greylag ganders seems to be testosterone-sensitive year-long and inappropriate status signalling of males may draw attacks towards their females. 相似文献
7.
Totzke U Hübinger A Dittami J Bairlein F 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2000,170(8):627-631
To investigate the proximate influence of a changing food availability on the seasonal fattening of migratory birds, garden
warblers (Sylvia borin) following postnuptial moult were food restricted once a week. Body mass, food intake, plasma hormone and metabolite levels
were measured and compared to birds which always had ad libitum food access. The food-restricted birds increased their body
mass significantly earlier than the controls. The accelerated fattening was initially not accompanied by hyperphagia and may
be due to either an increased food utilisation efficiency or a reduced metabolic rate. An increase of basal glucagon and corticosterone
and a decrease of insulin levels prior to fattening were not significant, however, they resulted in a significant decrease
of the insulin:glucagon ratio. This ratio was also lower in food-restricted birds than in control birds and may account for
the difference in the fattening progress. We conclude that seasonal fattening may be stimulated by a catabolic impulse which
could be imposed in free-living birds by a decrease of food availability and/or by an increase of energy expenditure. A negative
energy balance is hypothesised to be a common proximate factor affecting migratory as well as winter fattening.
Accepted: 24 August 2000 相似文献
8.
Franz Bairlein Johannes Fritz Alexandra Scope Ilse Schwendenwein Gabriela Stanclova Gertjan van Dijk Harro A. J. Meijer Simon Verhulst John Dittami 《PloS one》2015,10(9)
Many migrating birds undertake extraordinary long flights. How birds are able to perform such endurance flights of over 100-hour durations is still poorly understood. We examined energy expenditure and physiological changes in Northern Bald Ibis Geronticus eremite during natural flights using birds trained to follow an ultra-light aircraft. Because these birds were tame, with foster parents, we were able to bleed them immediately prior to and after each flight. Flight duration was experimentally designed ranging between one and almost four hours continuous flights. Energy expenditure during flight was estimated using doubly-labelled-water while physiological properties were assessed through blood chemistry including plasma metabolites, enzymes, electrolytes, blood gases, and reactive oxygen compounds. Instantaneous energy expenditure decreased with flight duration, and the birds appeared to balance aerobic and anaerobic metabolism, using fat, carbohydrate and protein as fuel. This made flight both economic and tolerable. The observed effects resemble classical exercise adaptations that can limit duration of exercise while reducing energetic output. There were also in-flight benefits that enable power output variation from cruising to manoeuvring. These adaptations share characteristics with physiological processes that have facilitated other athletic feats in nature and might enable the extraordinary long flights of migratory birds as well. 相似文献
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