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881.
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Catherine A. Palmer Richard A. Watts Amy P. Hastings Lynne D. Houck Stevan J. Arnold 《Journal of molecular evolution》2010,70(5):427-440
Sexual communication in plethodontid salamanders is mediated by a proteinaceous pheromone that a male delivers to a female during courtship, boosting her receptivity. The pheromone consists of three proteins from three unrelated protein families. These proteins are among a small group of pheromones known to affect female receptivity in vertebrates. Previously, we showed that the genes of two of these proteins (PRF and SPF) are prone to incessant evolution driven by positive selection, presumably as a consequence of coevolution with female receptors. In this report, we focus on the evolution of the third pheromone protein gene family, plethodontid modulating factor (PMF), to determine whether it shows the same pattern of diversification. We used RT-PCR in mental gland cDNA to survey PMF sequences from three genera of plethodontid salamanders (27 spp.) to measure rates of evolution, level of gene diversification, modes of selection, and types of amino acid substitution. Like PRF and SPF, PMF is produced by a multigene family characterized by gene duplication and high levels of polymorphism. PMF evolution is rapid, incessant, and driven by positive selection. PMF is more extreme in these dimensions than both PRF and SPF. Nestled within this extraordinary variation, however, is a signature of purifying selection, acting to preserve important structural and biochemical features of the PMF protein (i.e., secretion signal, cysteine residues, and pI). Although a pattern of persistent diversification exists at the molecular level, the morphological and behavioral aspects of the pheromone delivery system show evolutionary stasis over millions of years. 相似文献
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David P. Watts 《International journal of primatology》2003,24(2):451-454
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Corinne Watts Ian Stringer Greg Sherley George Gibbs Chris Green 《Journal of Insect Conservation》2008,12(3-4):359-370
Establishing new populations by transferring founder individuals from source populations has been effective for managing the recovery of many threatened species including some weta (Orthoptera: Anostostomatidae) in New Zealand. These large-bodied flightless insects are ‘flagship species’ for insect conservation in New Zealand and many are rare or threatened. The declining abundance of most weta species, particularly giant weta, can be attributed to the introduction of mammalian predators, habitat destruction, and habitat modification by introduced mammalian browsers. New populations of some weta have been established in locations, particularly on islands, where these threats have been eliminated or severely reduced in order to reduce the risk of extinction. Some populations were established to provide food for endemic vertebrates, ecosystem restoration and ready access for the general public. We illustrate how methods for both transferring weta and monitoring them have become more sophisticated by using a series of case studies. Other transfers of weta not included in the case studies are also summarised. We conclude by re-iterating the importance of documenting the transfer and post-release monitoring for all insect transfers, both for biogeographical reasons and to provide information to improve future transfers. 相似文献
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Phospholipid phase transitions as revealed by NMR 总被引:1,自引:0,他引:1
Aqueous dispersions of phospholipids can adopt a range of polymorphic phases which include bilayer and non-bilayer forms. Within the bilayer form, laterally separated phases may be induced as a result of surface electrostatic associations, thermotropic behaviour, lipid-protein interactions or because of molecular mismatch between chemically distinct phospholipids. Nuclear magnetic resonance (NMR) methods, designed to exploit the properties of either indigenous nuclei or isotopic labels introduced specifically into a phospholipid, can be used in some cases to describe the molecular properties and behaviour of phospholipids in both macroscopically distinct phases and in molecularly distinct phases within the same polymorphic state. If the molecular motion of phospholipids in co-existing phases is sufficiently different, NMR methods can, in principle, give estimates of the life-time of the phases and the rate of molecular exchange between the phases. 相似文献
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M. S. Watts 《The Western journal of medicine》1990,152(2):180-185
In susceptible persons emotional stress results in immediate sympathetic stimulation, with a vasomotor response that results in a high-output state and elevated blood pressure; the vasopressor response seems to be transient. There seems to be no longitudinal epidemiologic validation of the attractive hypothesis that transiently elevated blood pressures are the prelude to fixed hypertension, however. The acquisition of hypertension by populations abandoning their traditional mode of living has been attributed to the sociocultural stress inherent in westernization, but these studies usually have not taken into account concomitants of this type of acculturation, such as dietary changes and increased body weight. The inverse relationship of blood pressure levels to education could explain the development of hypertension when aspiration to upward mobility is thwarted. The severity of perceived occupational stress relates inversely to blood pressure, suggesting that familiarity with a job renders the demands made by the work environment more predictable and less threatening in terms of vasopressor response. 相似文献