已烯雌酚在人体各器官转移模型的变结构控制

本文通过线性系统极点配置,李雅普诺夫方法研究了已烯雌酚在人体各器官转移模型的变结构控制问题,得到了使系统尽快达到稳定平衡点的变结构控制器．该问题为生物模型综合控制问题的研究奠定了基础．     

HNHC: a triple resonance experiment for correlating the H2, N1(N3) and C2 resonances in adenine nucleobases of <Superscript>13</Superscript>C-, <Superscript>15</Superscript>N-labeled RNA oligonucleotides

A novel NMR pulse sequence has been developed that correlates the H2 resonances with the C2 and the N1 (N3) resonances in adenine nucleobases of ¹³C, ¹⁵N labeled oligonucleotides. The pulse scheme of the new 3D-HNHC experiment is composed of a ²J-¹⁵N-HSQC and a ¹J-¹³C-HSQC and utilizes large ²J(H2, N1(N3)) and ¹J(H2, C2) couplings. The experiment was applied to a medium-size ¹³C, ¹⁵N-labeled 36mer RNA. It is useful to resolve assignment ambiguities occurring especially in larger RNA molecules due to resonance overlap in the ¹H-dimension. Therefore, the missing link in correlating the imino H3 resonances of the uracils across the AU base pair to the H8 resonances of the adenines via the novel pulse sequence and the TROSY relayed HCCH-COSY (Simon et al. in J Biomol NMR 20:173–176 2001) is provided. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Experimental evidence that high levels of inbreeding depress sperm competitiveness

The effects of inbreeding on sperm quantity and quality are among the most dramatic examples of inbreeding depression. The extent to which inbreeding depression results in decreased fertilization success of a male’s sperm, however, remains largely unknown. This task is made more difficult by the fact that other factors, such as cryptic female choice, male sperm allocation and mating order, can also drive patterns of paternity. Here, we use artificial insemination to eliminate these extraneous sources of variation and to measure the effects of inbreeding on the competitiveness of a male’s sperm. We simultaneously inseminated female guppies (Poecilia reticulata) with equal amounts of sperm from an outbred (f = 0) male and either a highly (f = 0.59) or a moderately inbred (f = 0.25) male. Highly inbred males sired significantly fewer offspring than outbred males, but share of paternity did not differ between moderately inbred and outbred males. These findings therefore confirm that severe inbreeding can impair the competitiveness of sperm, but suggest that in the focal population inbreeding at order of a brother–sister mating does not reduce a male’s sperm competitiveness.     

Population genetics suggests effectiveness of habitat connectivity measures for the European tree frog in Switzerland

1.  Governmental authorities in many countries financially support the implementation of habitat connectivity measures to enhance the exchange of individuals among fragmented populations. The evaluation of the effectiveness of such measures is crucial for future management directions and can be accomplished by using genetic methods.
2.  We retraced the population history of the European tree frog in two Swiss river valleys (Reuss and Thur), performed comprehensive population sampling to infer the genetic structure at 11 microsatellite markers, and used first-generation migrant assignment tests to evaluate the contemporary exchange of individuals.
3.  Compared with the Thur valley, the Reuss valley has lost almost double the number of breeding sites and exhibited a more pronounced genetic grouping. However, similar numbers of contemporary migrants were detected in both valleys. In the Reuss valley, 81% of the migration events occurred within the identified genetic groups, whereas in the Thur valley migration patterns were diffuse.
4.  Our results show that the connectivity measures implemented in the Reuss valley facilitated effective tree frog migration among breeding sites within distances up to 4 km. Nevertheless, the Reuss valley exhibited high genetic differentiation, which reflected the impact of barriers to tree frog movement such as the River Reuss. By contrast in the Thur valley, a larger number of breeding sites have been preserved and high admixture indicated exchange of individuals at distances up to 16 km.
5.   Synthesis and applications . We show that genetic methods can substantiate the effectiveness of connectivity measures taken in conservation management at the landscape scale. We urge responsible authorities from both river valleys to continue implementing connectivity measures and to create a dense network of breeding sites, as spatial gaps of 8 km are rarely traversed by tree frogs.     

What Hanuman langur males know about female reproductive status

In species with a high risk of infanticide, a conflict of interest exists between the sexes over the amount of paternity information that is available to males. While females are expected to keep males unaware of their reproductive status in order to confuse paternity, selection should favor those male traits that enhance the males' assessment of female status and consequently of paternity probability. In Hanuman langurs (Semnopithecus entellus), a species that is extremely vulnerable to infanticide, females have been shown to successfully conceal the exact timing of ovulation from males--perhaps because they exhibit no sexual swelling and mate during all reproductive phases, including gestation. Nevertheless, it remains unclear whether males have hitherto unrecognized information about females' reproductive condition on a broader level that could still enhance male reproductive success. We investigated male assessment of female reproductive states in a population of wild Hanuman langurs as indicated by changes in male behavior, such as rates of copulations, anogenital inspections, and consortships, in relation to different female receptive periods (pregnant, fertile-nonconceptional, and conceptional). Our data indicate that males were able to discern qualitatively distinct reproductive states. Males were more interested in fertile than pregnant females, as indicated by higher copulation rates. Based on consortships, males distinguished fertile from nonfertile phases, as well as fertile, nonconceptional receptive periods from conceptional ones. Hanuman langur males are thus not as unaware of female reproductive condition as previously thought, supporting the idea of an ongoing battle of the sexes over paternity information. However, granting some knowledge while at the same time concealing the exact day of ovulation may also reflect a pure female strategy of balancing paternity concentration with paternity confusion, which is the most likely strategy in this system with high infanticide risk and male defense of infants.     

Extrapair paternity and mate choice in a chickadee hybrid zone

The dynamics of hybrid zones are likely to be influenced greatlyby patterns of mate choice, including "cryptic" choice mediatedthrough extrapair copulations. To understand changes in hybridzones over time and space, a detailed examination of matingpatterns and correlates is needed. We studied the role of extrapairfertilizations (EPFs) in the breeding biology of hybridizingblack-capped and Carolina chickadees in southeastern Pennsylvaniaover 4 years, using microsatellite DNA markers. We detectedextrapair offspring (EPO) in 56% of 90 broods examined; theseaccounted for at least 26% of 477 offspring. Chickadees do notappear to use EPFs to reduce costs of heterospecific pairing:EPFs were no more likely to occur in genetically dissimilar(heterospecific) social pairs than in pairs where social mateswere genetically similar. However, females paired with black-capped–likemales were more likely to have EPO. Females that acquired EPFsdid not obtain these from males genetically similar to themselves;instead, all females, regardless of their genotype or that oftheir social mate, tended to prefer Carolina-like males as extrapairpartners. There was no relationship between the presence ofEPO and hatching or fledging success. High rates of extrapairpaternity and apparent female preference for Carolina-like malessuggest that mate choice is an important influence in ongoingnorthward movement of this hybrid zone.     

Ecological specialization correlates with genotypic differentiation in sympatric host-populations of the pea aphid

The pea aphid, Acyrthosiphon pisum, encompasses distinct host races specialized on various Fabaceae species, but the extent of genetic divergence associated with ecological specialization varies greatly depending on plant and geographic origins of aphid populations. Here, we studied the genetic structure of French sympatric pea aphid populations collected on perennial (pea and faba bean) and annual (alfalfa and red clover) hosts using 14 microsatellite loci. Classical and Bayesian population genetics analyses consistently identified genetic clusters mostly related to plant origin: the pea/faba bean cluster was highly divergent from the red clover and the alfalfa ones, indicating they represent different stages along the continuum of genetic differentiation. Some genotypes were assigned to a cluster differing from the one expected from their plant origin while others exhibited intermediate genetic characteristics. These results suggest incomplete barriers to gene flow. However, this limited gene flow seems insufficient to prevent ecological specialization and genetic differentiation in sympatry.