The ant speciesLeptothorax tuberum was shown to be predominantly monogynous. Queens usually mate once only but some nests may have a multiply-mated queen or
are partially or serially polygynous. As expected from these results, within nest relatedness between workers and between
workers and alate queens was found to be high. Almost fifty percent of nests had no nest queen which may indicate high queen
mortality, queens leaving to found new nests or nest fragmentation. Observed female investment frequencies (IFo) were not significantly different from those expected on the basis of worker control of sexual production and the relatedness
estimates of workers to alate queens and workers to males calculated from isozyme data (IFE). These values were not consistent with queen control. There was no evidence for lower IFos in queenless nests nor for higher IFos in larger nests classified by worker number. When nests were classified by sexual productivity, however, there was a strong
rank correlation between productivity and female bias. This is the first study of an ant species to test observed IF against
expected IF calculated without inferring between caste relatedness from worker data or pooling of data from different castes. 相似文献
Transgenic Research - To inform the ecological risk assessment (ERA) of a transgenic crop with multiple insecticidal traits combined by conventional breeding (breeding stack), a comparative field... 相似文献
The unwarranted interference of some environmental non-governmental organisations (ENGOs) in decision-making over genetically modified (GM) crops has prompted calls for politics to be removed from the regulatory governance of these products. However, regulatory systems are inevitably political because their purpose is to decide whether the use of particular products will help or hinder the delivery of public policy objectives. ENGOs are most able to interfere in regulatory decision-making when policy objectives and decision-making criteria are vague, making the process vulnerable to disruption by organisations that have a distinct agenda. Making regulatory decision-making about GM crops and other green biotechnology more resistant to interference therefore requires better politics not the removal of politics. Better politics begins with political leadership making a case for green biotechnology in achieving food security and other sustainable development goals. Such a policy must involve making political choices and cannot be outsourced to science. Other aspects of better politics include regulatory reform to set policy aims and decision-making criteria that encourage innovation as well as control risk, and engagement with civil society that discusses the values behind attitudes to the application of green biotechnology. In short, green biotechnology for sustainable development needs better politics to counter well-organised opposition, to encourage innovation, and to build the trust of civil society for these policies. Removing politics from regulatory governance would be a gift to ENGOs that are opposed to the use of biotechnology.
Phosphoglucomutase (PGM) and trehalase (Tre) isoenzymes of five species of Simulium blackflies (Diptera: Simuliidae), vectors of onchocerciasis in Venezuela, were investigated by means of a portable electrophoresis field kit. Tre differed between S. incrustatum and S. oyapockense s.l. Electrophoretic variation of Tre in other members of the S. amazonicum and S. incrustatum groups merit further investigation. PGM appears to be more useful for separating populations within species complexes. Multiple populations and/or seasonal changes in population structure of S. guianense s.l., S. exiguum s.l. and S. metallicum s.l. were inferred from elecrophoretic variation of PGM. 相似文献
Colonies of the European hornet, Vespa crabro, are typically founded by a single queen mated to a single male. From the resulting colony relatedness pattern we predicted strong worker-queen conflict over male production where both the workers and the queen attempt to produce the colony's males. To test for this conflict, male production was studied in 15 hornet nests using a combination of DNA microsatellite analysis (282 males), worker ovary dissections (500 workers from eight nests) and 50 h of observation (four nests). In contrast to our prediction, the data show that hornet males are queens' sons, that workers never attempt to lay eggs, rarely have activated ovaries, and that there is no direct aggression between the queen and the workers. This contrasts with other data for vespine wasps, which support relatedness predictions. Dolichovespula arenaria has the same kin structure as V. crabro and workers produce males in many colonies. The similarity between these two species makes it difficult to explain why workers do not reproduce in V. crabro. Self-restraint is expected if worker reproduction significantly reduces colony productivity but there is no obvious reason why this should be important to V. crabro but not to D. arenaria. Alternatively, queen control may be important. The absence of expressed queen-worker conflict rules out physical control. Indirect pheromonal control is a possibility and is supported by the occurrence of royal courts and queen pheromone in Vespa but not Dolichovespula. Pheromonal queen control is considered evolutionarily unstable, but could result from a queen-worker arms race over reproductive control in which the queen is ahead. The genetic data also revealed diploid males in one colony, the first example in the vespine wasps, and two colonies with double matrilines, suggesting that occasional usurpation by spring queens occurs. 相似文献
One of the major environmental concerns over genetically modified (GM) crops relates to transgene movement into wild relatives. The pattern of hybridization ultimately affects the scale and rapidity of ecological change and the feasibility of containment. A new procedure for quantifying hybrid formation over large areas is described. Remote sensing was used to identify possible sites of sympatry between Brassica napus and its progenitor species across 15 000 km2 of south-east England in 1998. Two sympatric populations with B. rapa and one with B. oleracea were found over the entire survey area. Every newly recruited plant in these populations in 1999 was screened for hybrid status using flow cytometry and molecular analyses. One hybrid was observed from the 505 plants screened in the B. rapa populations but none of the nine B. oleracea recruits were hybrids. Measures to minimize gene flow are suggested, and a procedure for the post-release evaluation and containment of GM cultivars is proposed. 相似文献
Many gastrointestinal meal-related signals are transmitted to the central nervous system via the vagus nerve and thereby control changes in meal size. The c-Fos-positive neuron has been used as a marker of neuronal activation after lipid meals to examine the contribution of a selective macronutrient on brain neurocircuit activity. In rats fed Intralipid, the c-Fos-positive neurons were highly stimulated in the nucleus of the solitary tract (NTS) and in the hypothalamus, including the paraventricular nucleus (PVN), arcuate nucleus of the hypothalamus (ARC), and ventromedial hypothalamus at 4 h lipid feeding. However, c-Fos-like immunoreactivity was markedly attenuated in these brain regions when chylomicron formation/secretion was blocked by Pluronic L-81. After lymph was diverted from the lymph cannulated animals, the rats had a lower number of c-Fos-positive cells in the NTS and ARC. In contrast, the rats had higher c-Fos-positive neurons in PVN. The present study also revealed that c-Fos-positive neurons induced by feeding of Intalipid were abolished by CCK type 1 receptor antagonist, Lorglumide. We conclude that the formation and/or secretion of chylomicron are critical steps for initiating neuronal activation in the brain. 相似文献
Transgenic crops producing insecticidal proteins from Bacillus thuringiensis (Bt) provide economic, environmental and health benefits by maintaining or increasing crop yields with fewer applications of
insecticide. To sustain these benefits, it is important to delay the evolution of insect resistance to the proteins, and to
ensure that the proteins do not harm non-target organisms, particularly those that may control secondary pests that would
otherwise flourish because of reduced insecticide applications. Vip3A is a Bt vegetative insecticidal protein that is active against lepidopterous pests. It has a different mode of action from other
proteins for control of Lepidoptera in current Bt crops, and when combined with these proteins, it should help to delay the evolution of pest resistance to Bt crops. This paper presents data on the effects of Vip3A on non-target organisms, and an ecological risk assessment of MIR162
maize, which expresses Vip3Aa20. Laboratory studies indicate few adverse effects of Vip3A to non-target organisms: 11 of 12
species tested showed no adverse effects when exposed to high concentrations of Vip3A relative to estimated exposures resulting
from cultivation of MIR162 maize. Daphnia magna exposed to Vip3Aa20 were unaffected in terms of survival or fecundity, but grew slightly more slowly than unexposed controls.
The data indicate that cultivation of MIR162 maize poses negligible risk to non-target organisms, and that crops producing
Vip3A are unlikely to adversely affect biological control organisms such that benefits from reduced insecticide applications
are lost. 相似文献
Problem formulation is the first step in environmental risk assessment (ERA) where policy goals, scope, assessment endpoints,
and methodology are distilled to an explicitly stated problem and approach for analysis. The consistency and utility of ERAs
for genetically modified (GM) plants can be improved through rigorous problem formulation (PF), producing an analysis plan
that describes relevant exposure scenarios and the potential consequences of these scenarios. A properly executed PF assures
the relevance of ERA outcomes for decision-making. Adopting a harmonized approach to problem formulation should bring about
greater uniformity in the ERA process for GM plants among regulatory regimes globally. This paper is the product of an international
expert group convened by the International Life Sciences Institute (ILSI) Research Foundation. 相似文献