Morphology and coexistence of congeneric ectoparasite species: reinforcement of reproductive isolation?

Assuming that differences or similarities in morphology among congeneric parasite species living in the same habitat are not a random pattern, several hypotheses explaining morphological differences were tested: (i) reproductive isolation, (ii) niche restriction resulting from competition, and (iii) niche specialization. Congeneric monogenean (platyhelminth) ectoparasites parasitizing the gills of one host species were used as an ecological model. Morphometric distances of the attachment organ and morphometric distances of the copulatory organ between species pairs were calculated, Levin's niche size and Renkonen niche overlap indices were applied. Our results support the prediction that the function of niche segregation is to achieve reproductive isolation of related species in order to prevent hybridization (reinforcement of reproductive barriers). Parasite species living in the same niche differ greatly in the size of copulatory organ. Moreover, species coexistence is facilitated by an increase in morphometric distances of copulatory organ and niche centre distances. Our results also show that species living in overlapping niches have similar attachment organs, which supports the prediction that morphologically similar species have the same ecological requirements within one host and suggests small effects of interspecific competition for the evolution of morphological diversity of attachment organs. Specialist adaptations also seem to facilitate species coexistence and affect the niche distribution within host species. Parasite species that can colonize more than one host species, i.e. generalists, occupy more distant niches within host species than strictly host-specific parasites. © 2002 The Linnean Society of London, Biological Journal of the Linnean Society , 2002, 76, 125–135.     

烟青虫感染核型多角体病毒后围食膜的病变

昆虫的围食膜是衬在昆虫中肠内一种网状的结构,它可充作虫体抵御外来病原侵染的一道屏障。关于鳞翅目昆虫幼虫感染了昆虫病毒后围食膜的病变问题,国内外鲜有报道。尤锡镇和康慧娟(1985)曾以实验证明家蚕围食膜对核型多角体病毒有灭活作用,而且认为核型多角体病毒不能侵染和破坏围食膜。Derksen和Granados(1988)则证明染病幼虫的围食膜因不同杆状病毒(包括两种核型多角体病     

κ-卡拉胶琥珀酰基化衍生物的抗氧化活性研究

对κ-卡拉胶进行酸降解得到三种卡拉胶低聚糖,并进一步琥珀酰基化得到分子量分别为2720、4000和5960的κ-卡拉胶琥珀酰衍生物(A、B和C)。对产物进行FT-IR表征,并测得其琥珀酰基取代度(DS)分别为0.61、0.29和0.83。检测了三种κ-卡拉胶琥珀酰衍生物对超氧阴离子自由基O2.-、DPPH自由基、羟基自由基.OH以及过氧化氢的清除活性。结果表明:随着取代度的增加,其清除超氧阴离子自由基O2.-和DPPH自由基的能力增强;随着分子量的增加,其清除羟基自由基.OH和过氧化氢的能力增强。这可能与衍生物的羟基含量、取代基团的性质以及取代度等因素有关。     

Somatoform disorders among patients attending walk-in clinics in Trinidad: prevalence and association with depression and anxiety

Objectives Somatoform disorders are common in international primary care settings, but have been little studied in the developing world. The objective of this study was to determine the prevalence of severe undifferentiated somatoform disorder, and its relationship to depression and anxiety, among patients attending walk-in clinics in Trinidad.Methods The study participants, who were all aged 18 years or older and attending walk-in clinics at 16 randomly selected health centres, were surveyed between May and August 2007 using the PRIME-MD questionnaire.Results There were 594 participants (the response rate was 92%), of whom 72.7% were female. Their ages ranged from 18 to 93 years, and 54.5% were over 50 years of age. In total, 37.2% were married and 25.9% were single. Indo-Trinidadians represented 43.1% and Afro-Trinidadians represented 36% of the study sample; 56.5% of the participants reported that their income was less than US$ 400 per month, and 65.7% were unemployed. At walk-in clinics in Trinidad, the estimated prevalence of severe undifferentiated somatoform disorder was 10.3% (95% CI: 7.86–12.74), that of hypochondriasis was 28.5% (95% CI: 24.9–32.1), and that of body dysmorphic disorder was 15.8% (95% CI: 11.9–18.7). Severe undifferentiated somatoform disorder was statistically significantly associated with gender and ethnicity but not with age, level of education, employment status or income. Chi-square testing found significant associations between the presence of severe undifferentiated somatoform disorder and both depression and anxiety (P < 0.05), between hypochondriasis and both anxiety and depression (P < 0.05), and between body dysmorphic disorder and depression (P < 0.05) but not anxiety. Regression analysis suggested that the demographic features that predicted severe undifferentiated somatoform disorder were being female or Indo-Trinidadian.Conclusions Walk-in clinics in Trinidad that serve older patients on a lower income have a high proportion of patients with somatoform disorders as measured by the PRIME-MD scale. These patients exhibit many features of anxiety and depression. These findings have implications for medical training and service delivery.     

Distribution of amiloride-sensitive sodium channels in the oral cavity of the hamster

The distribution of amiloride-sensitive sodium channels (ASSCs) in taste buds isolated from the oral cavity of hamsters was assessed by patch clamp recording. In contrast to the case for rats, taste cells from the fungiform, foliate and vallate papillae and from the soft palate all contain functional ASSCs. The differential distribution of ASSCs between the hamster and the rat may be important for understanding the physiology underlying the differing behavioral responses of these species to sodium salts.      

锌对铅染毒新生大鼠成骨细胞增殖分化的影响

目的:探讨铅锌联合染毒对乳鼠颅骨成骨细胞增殖分化的影响。方法:分离并培养原代成骨细胞,加入不同浓度铅、锌培养48h,检测其对成骨细胞增殖的作用;用碱性磷酸酶试剂盒检测ALP活力。结果:在染铅48h后,当铅浓度≥10μmol/L时,细胞增殖功能下降(P<0.05);加锌干预48h后,铅+锌组细胞增殖功能均高于各自单独染铅组,其中铅(1μmol/L、10μmol/L)+锌(50μmol/L)组、铅(10)+锌(100)组与对照组间的差异具有统计学意义(P<0.05)。铅干预48h后,100μmol/L铅组的ALP活力显著下(P<0.05),给予锌干预的铅锌联合染毒组,各组ALP活力均有增加,其中铅(1μmol/L、10μmol/L)+锌(50μmol/L)组ALP活力均高于对照组,而铅(100μmol/L)+锌(50μmol/L)组ALP活力低于对照组,差异均有统计学意义(P<0.05)。结论:铅对成骨细胞有毒性作用,影响其增殖和分化功能;50μmol/L锌在一定程度上可以拮抗铅对成骨细胞增殖和分化功能的损伤,且对ALP活力的作用更显著,为铅中毒骨病的防治提供一定的科学依据。     

Early Tertiary fossil plants and paleoclimate of Lanzhou Basin

Fossil plants from the lower part of Xianshuihe Formation in the Lanzhou Basin, Gansu Province were studied. The flora contains 29 species, representing 20 genera and 12 families, which include Lauraceae ( Daphnogene ), Lardizabalaceae ( Akebia ), Berberidaceae ( Berberis ), Ulmaceae ( Planera, Ulmus, Zelkova ), Betulaceae ( Alnus, Carpinus ), Myricaceae( Myrica ), Salicaceae ( Populus, Salix), Myrsinaceae(Ardisia), Rosaceae ( Prunus, Sorbus, Sorbaria, Spiraea ), Leguminosae ( Gleditsia, Sophora), Anacardiaceae (Rhus), Caprifoliaceae(Viburnum). An analysis of the floristic elements and their foliar physiognomy shows that most members of the flora are deciduous broad-leaved trees or shrubs with a few evergreen shrubs. The most noteworthy species is Rhus turcomanica which was present in the Middle Eocene to Late Eocene of Central Asia (Kazakhstan, Turkmenistan). Generally, Rhus turcomanica occurred at the same beds as Palibinia, an extinct fossil plant whose presence indicates a subtropical dry climate. Another species, Sorbaria callicomifolia Kornilova was present from the Early Oligocene to Early Miocene of Central Asia (Kazakhstan and Turkmenistan). According to an analysis of spores and pollen, this flora contains over 20 species. It is predominated by the angiosperm pollen. There appeared Ephedripites and Nitrariadites which were important elements in the dry area. Ephedripites was found from the Upper Cretaceous to Early Tertiary. Nitrariadites occurred in the Late Miocene, whereas Rhus turcomanica and Sorbaria callicomifolia were both reported in the subtropical dry area from the Middle Eocene to Early Oligocene. The latest record of Rhus turcomanica is from the Middle Eocene to Early Oligocene of Central Asia. The presence of this element in the lower part of Xianshuihe Formation may indicate that itsage is the latest stage of the Early Oligocene.     

Pyrazole compound BPR1P0034 with potent and selective anti-influenza virus activity

Background

Influenza viruses are a major cause of morbidity and mortality around the world. More recently, a swine-origin influenza A (H1N1) virus that is spreading via human-to-human transmission has become a serious public concern. Although vaccination is the primary strategy for preventing infections, influenza antiviral drugs play an important role in a comprehensive approach to controlling illness and transmission. In addition, a search for influenza-inhibiting drugs is particularly important in the face of high rate of emergence of influenza strains resistant to several existing influenza antivirals.

Methods

We searched for novel anti-influenza inhibitors using a cell-based neutralization (inhibition of virus-induced cytopathic effect) assay. After screening 20,800 randomly selected compounds from a library from ChemDiv, Inc., we found that BPR1P0034 has sub-micromolar antiviral activity. The compound was resynthesized in five steps by conventional chemical techniques. Lead optimization and a structure-activity analysis were used to improve potency. Time-of-addition assay was performed to target an event in the virus life cycle.

Results

The 50% effective inhibitory concentration (IC₅₀) of BPR1P0034 was 0.42 ± 0.11 μM, when measured with a plaque reduction assay. Viral protein and RNA synthesis of A/WSN/33 (H1N1) was inhibited by BPR1P0034 and the virus-induced cytopathic effects were thus significantly reduced. BPR1P0034 exhibited broad inhibition spectrum for influenza viruses but showed no antiviral effect for enteroviruses and echovirus 9. In a time-of-addition assay, in which the compound was added at different stages along the viral replication cycle (such as at adsorption or after adsorption), its antiviral activity was more efficient in cells treated with the test compound between 0 and 2 h, right after viral infection, implying that an early step of viral replication might be the target of the compound. These results suggest that BPR1P0034 targets the virus during viral uncoating or viral RNA importation into the nucleus.

Conclusions

To the best of our knowledge, BPR1P0034 is the first pyrazole-based anti-influenza compound ever identified and characterized from high throughput screening to show potent (sub-μM) antiviral activity. We conclude that BPR1P0034 has potential antiviral activity, which offers an opportunity for the development of a new anti-influenza virus agent.