家禽的性别鉴定方法

现代家禽生产,祖代鸡通过释肛鉴定性别,父母代鸡以羽速（快慢羽）判定公母,而商品代鸡则以羽色自别雌雄。常规性别鉴定方法耗资费力,且慢羽基因（K）与内源病毒基因（ev-21）紧密连锁,导致慢羽鸡群免疫反应降低,成活率和产蛋性能下降。以鉴定W染色体上性连锁DNA序列或基因为基础,从分子水平上鉴定家禽性别的研究有望填补家禽性别鉴定空白。     

Honeybee guards do not use food-derived odors to recognize non-nest mates: a test of the Odor Convergence hypothesis

Honeybee (Apis mellifera) colonies rob honey from each other during periods of nectar shortage. Persistent robbing can killweak colonies. Primarily responsible for preventing robbingare guard bees. Previous research has shown that the probabilityof both nest mate and non-nest mate workers being acceptedby guards at the nest entrance increases as nectar availability increases. The mechanism responsible for this change in guardacceptance can be explained by two competing hypotheses: OdorConvergence and Adaptive Threshold Shift. In this study wetested the Odor Convergence hypothesis. The acceptance by guardsat the nest entrance of workers transferred between four coloniesthat had been fed either odorless sucrose syrup (two colonies)or diluted heather honey (Calluna vulgaris) (two colonies)was measured for 3 days before feeding and during 2 weeks offeeding. Despite the large sample sizes, the probability ofguards accepting non-nest mates was not affected by the similaritiesor dissimilarities in food odor between guards' and non-nestmates' colonies. This finding contrasts with the accepted wisdom that food odors are important in nest mate recognition in honeybeesand the data, therefore, strongly reject the Odor Convergencehypothesis.     

Fisher判别分析法在川金丝猴亚种鉴定中的应用

根据川金丝猴头骨标本的性征指标数据,应用Fisher判别分析方法,对川金丝猴的亚种进行了判别分类．     

Shedding light on health and disease using molecular beacons.

The detection and identification of pathogens is often painstaking due to the low abundance of diseased cells in clinical samples. The genomic sequences of the pathogen can be amplified through methods such as the polymerase chain reaction and nucleic acid sequence-based amplification, but the nucleic acid targets are often lost among other unintended products of amplification. Novel nucleic acid probes known as molecular beacons have been developed allowing for the rapid and specific detection of genetic markers of a disease. Molecular beacons are hairpin-forming oligonucleotides labelled at one end with a quencher and at the other end with a fluorescent reporter dye. In the absence of target, the fluorescence is quenched. In the presence of target, the hairpin structure opens upon beacon/target hybridisation, resulting in the restoration of fluorescence. The ability to transduce target recognition into a fluorescence signal with high signal-to-background ratio, coupled with an improved specificity, has allowed molecular beacons to enjoy a wide range of biological and biomedical applications. Here, we describe the basic features of molecular beacons, review their applications in disease detection and diagnosis and discuss some of the issues and challenges of in vivo studies. The aim of this paper is to foster the development of new molecular beacon-based assays and to stimulate the application of this technology in laboratory and clinical studies of health and disease.     

The impact of past pandemics on economic and gender inequalities

This paper estimates how previous major pandemic events affected economic and gender inequalities in the short- to medium run. We consider the impact of six major pandemic episodes – H3N2 Flu (1968), SARS (2003), H1N1 Swine Flu (2009), MERS (2012), Ebola (2014), and Zika (2016) – on cross-country inequalities in samples of 46–167 countries observed over 1950–2019. Results show that the past pandemics have moderately increased income inequality in the affected countries in the period of four to five years after the pandemic’s start. On the other hand, we do not find any robust negative impacts on wealth inequality. The results concerning gender inequality are less consistent, but we find some evidence of declining gender equality among the hardest hit countries. Moreover, the gender gap in unemployment grew within the four years after the onset of the pandemic.     

Comparison between touchscreen operant chambers and water maze to detect early prefrontal dysfunction in mice

The relative lack of sensitive and clinically valid tests of rodent behavior might be one of the reasons for the limited success of the clinical translation of preclinical Alzheimer's disease (AD) research findings. There is a general interest in innovative behavioral methodology, and protocols have been proposed for touchscreen operant chambers that might be superior to existing cognitive assessment methods. We assessed and analyzed touchscreen performance in several novel ways to examine the possible occurrence of early signs of prefrontal (PFC) functional decline in the APP/PS1 mouse model of AD. Touchscreen learning performance was compared between APP/PS1-21 mice and wildtype littermates on a C57BL/6J background at 3, 6 and 12 months of age in parallel to the assessment of spatial learning, memory and cognitive flexibility in the Morris water maze (MWM). We found that older mice generally needed more training sessions to complete the touchscreen protocol than younger ones. Older mice also displayed defects in MWM working memory performance, but touchscreen protocols detected functional changes beginning at 3 months of age. Histological changes in PFC of APP/PS1 mice indeed occurred as early as 3 months. Our results suggest that touchscreen operant protocols are more sensitive to PFC dysfunction, which is of relevance to the use of these tasks and devices in preclinical AD research and experimental pharmacology.     

Effects of search experience in a resource-heterogeneous environment on the oviposition decisions of the seed beetle, Callosobruchus maculatus (F.)

Abstract.  1. This study investigates how female seed beetles, Callosobruchus maculatus , distribute their eggs on various-sized seeds when the size of seed was varied during the egg-laying period.
2. Beetles were allowed to lay eggs on one of three arrays of 64 adzuki beans ( Vigna angularis ). Each array contained four size classes of seed, ranging from small (5.0–5.5 mm diameter) to large (6.5–7.0 mm), but differed in how they were distributed within the environment. In the most heterogeneous condition (the 64-patch design), the four sizes were interspersed, while in the least heterogeneous condition (the four-patch design) they were grouped into four separate blocks. Thus, a beetle exploring the 64-patch design would frequently encounter all four seed sizes, whereas a beetle exploring the four-patch design would only rarely encounter a change in bean size.
3. Beetles experiencing greater seed size heterogeneity were more likely to lay eggs on larger seeds, whereas those in the blocked condition were more likely to oviposit on small seeds. Beetle responses to seed size heterogeneity suggest that the degree of preference for large seeds depends on a female's recent experience.
4. Female beetles exhibited size discrimination throughout their egg-laying process; however, there was a trade-off between seed size and egg discrimination (i.e. avoiding those seeds already containing developing eggs) in response to the change in fitness gained from either laying on larger seeds or lower egg-load seeds during the egg-laying process.
5. Our model provides the first evidence that evolving seed size discrimination ability is adaptive for the seed beetle with egg-discrimination ability.     

Temporal mechanisms influencing gender expression and pollen flow within a self-incompatible perennial,Amianthium muscaetoxicum (Liliaceae)

Summary Temporal mechanisms that influence the synchrony of gender expression and the patterns of withinplant pollen flow were examined in Amianthium muscatoxicum. In this species self-incompatible pollinations can clog stigmas, interfere with the growth of outcrossed pollen tubes, and reduce fecundity. The majority of flowers have partial dichogamy: a two-day period of pollen dehiscence and a four-day period of pollen viability are nested in a six-day period of pistil viability. An indeterminate flowering sequence among flowers on the same plant and partial dichogamy within flowers help reduce pollen flow within the whole plant. The combined effects at both of these levels should reduce pollen wastage and lower the incidence of stigma clogging by incompatible self pollen.     

Coexistence of pseudogamous and sexual planthoppers of the genus Ribautodelphax (Homoptera, Delphacidae)

ABSTRACT.

• 1 The occurrence of pseudogamous triploid females in populations of the diploid species Ribautodelphax pungens (Ribaut) was studied throughout Europe.
• 2 Considerable differences in triploid frequencies were found between populations but no regular geographic pattern was discerned.
• 3 Within populations triploid frequencies proved to be stable from generation to generation.
• 4 The twofold reproductive advantage of the pseudogamous triploid females is counterbalanced by active mate discrimination by diploid males against the pseudogamous triploid females in populations with high triploid frequencies.
• 5 Sexual diploid and pseudogamous triploid females showed no differences in phenology.
• 6 Differential winter mortality was found between diploid and triploid larvae.

     

Gender difference in the relationship of performance in the handgrip and standing long jump tests to lean limb volume in young adults

Groups of young, adult males and females performed the handgrip and standing long jump tests. Their total forearm and leg volumes were calculated from a series of circumference and length measurements, and the lean volumes (bone + muscle) calculated by taking the skinfold thickness into consideration. In the handgrip, the mean female performance was 298 N compared with 496 N for the males. In the standing long jump, mean performance expressed as distance x body mass was 87.3 kg.m for females compared with 137.7 kg.m for males. These superior performances of males could simply reflect their greater muscle mass, as the mean lean volumes of female and male limbs respectively were 0.54 l and 0.89 l for forearms, and 11.82 l and 14.82 l for the two legs. However, when the performances of males and females were grouped by lean limb volume, it was found that while in both tests there were linear relationships, males and females did not share a common line. In both tests the male relationship was at a higher level than the female; therefore, for a given lean volume, the male performance was significantly superior to that of the female. The gender difference found in this study has not been seen in other studies in which the performance of skeletal muscle has been related to the cross-sectional area of the active muscles and the possible reasons for the differences are considered.