Movements of feral camels in central Australia determined by satellite telemetry

Movements of two female one-humped camels in central Australia were tracked using satellite telemetry between March 1986 and July 1987. During that time both animals travelled a minimum distance of over 1000 km within a radius of 125 km for one animal, and 200 km for the other. However, their movements were uite punctuated and both animals spent periods of up to several months in rleatively small areas before moving over longer distances to new areas. Both camels moved at greater rates overnight. An activity index, probably measuring feeding rate, declined during the study period for both animals. Patchy and sporadic rainfall may explain some of these results

Facultative Aestivation in a Tropical Freshwater Turtle Chelodina rugosa

Abstract-1. Chelodina rugosa dug from aestivation sites at the end of the dry season were immediately alert and well coordinated. 2. Compared with non-aestivating animals, aestivating turtles had 20% higher plasma osmotic pressure and 7% higher sodium. Coupled with a small, but significant weight gain upon return to the water, this suggested the occurrence of minor dehydration in aestivating animals. 3. Plasma lactate levels of aestivating animals were low, averaging 1.99 mmol/1, consistent with aerobic rather than anaerobic metabolism having sustained their long period under ground. 4. No evidence was seen of dramatic physiological specialization. Aestivation in this species is interpreted as a primarily behavioural adaptation, made possible by typically reptilian abilities to tolerate a wide range in plasma electrolytes and to survive long periods without feeding

Human macrophages differentiated in the presence of vitamin D3 restrict dengue virus infection and innate responses by downregulating mannose receptor expression

ABSTARCT: Severe dengue disease is associated with high viral loads and overproduction of pro-inflammatory cytokines, suggesting impairment in the control of dengue virus (DENV) and the mechanisms that regulate cytokine production. Vitamin D3 has been described as an important modulator of immune responses to several pathogens. Interestingly, increasing evidence has associated vitamin D with decreased DENV infection and early disease recovery, yet the molecular mechanisms whereby vitamin D reduces DENV infection are not well understood. METHODS AND PRINCIPAL FINDINGS: Macrophages represent important cell targets for DENV replication and consequently, they are key drivers of dengue disease. In this study we evaluated the effect of vitamin D3 on the differentiation of monocyte-derived macrophages (MDM) and their susceptibility and cytokine response to DENV. Our data demonstrate that MDM differentiated in the presence of vitamin D3 (D3-MDM) restrict DENV infection and moderate the classical inflammatory cytokine response. Mechanistically, vitamin D3-driven differentiation led to reduced surface expression of C-type lectins including the mannose receptor (MR, CD206) that is known to act as primary receptor for DENV attachment on macrophages and to trigger of immune signaling. Consequently, DENV bound less efficiently to vitamin D3-differentiated macrophages, leading to lower infection. Interestingly, IL-4 enhanced infection was reduced in D3-MDM by restriction of MR expression. Moreover, we detected moderate secretion of TNF-α, IL-1β, and IL-10 in D3-MDM, likely due to less MR engagement during DENV infection. CONCLUSIONS/SIGNIFICANCE: Our findings reveal a molecular mechanism by which vitamin D counteracts DENV infection and progression of severe disease, and indicates its potential relevance as a preventive or therapeutic candidate

The exceptional longevity of an egg-laying mammal, the short-beaked echidna (Tachyglossus aculeatus) is associated with peroxidation-resistant membrane composition

The echidna Tachyglossus aculeatus is a monotreme mammal from Australia that is exceptionally long-living. Its documented maximum lifespan of 50 years is 3.7 times that predicted from its body mass. Other exceptionally long-living mammals (naked mole-rats and humans) are known to have peroxidationresistant membrane composition, raising the question about echidnas. Phospholipids were extracted from skeletal muscle, liver and liver mitochondria of echidnas and fatty acid composition measured. As with other exceptionally long-living mammals, membrane lipids of echidna tissues were found to have a lower content of polyunsaturates and a higher content of monounsaturates than predicted for their body size. The peroxidation index (=peroxidation susceptibility) calculated from this membrane composition was lower-than-expected for their body size, indicating that the cellular membranes of echidnas would be peroxidation-resistant. Additionally when the calculated peroxidation index was plotted against maximum lifespan, the echidna values conformed to the relationship for mammals in general. These findings support the membrane pacemaker theory of aging and emphasise the potential importance of membrane fatty acid composition in aging and in the determination of maximum longevity