Testing Mechanisms of the Dilution Effect: Deer Mice Encounter Rates, Sin Nombre Virus Prevalence and Species Diversity

Species diversity has been shown to decrease prevalence of disease in a variety of host–pathogen systems, in a phenomenon termed the Dilution Effect. Several mechanisms have been proposed by which diversity may decrease prevalence, though few have been tested in natural host-pathogen systems. We investigated the mechanisms by which diversity influenced the prevalence of Sin Nombre virus (SNV), a directly transmitted virus in deer mice (Peromyscus maniculatus). We monitored both intra and interspecific encounters of deer mice using foraging arenas at five sites in the Great Basin Desert with disparate levels of species diversity to examine two potential mechanisms which may contribute to the dilution of SNV prevalence: (1) reduced frequency of encounters between deer mice, or (2) reduced duration of contacts between deer mice. We also investigated the relationship between deer mouse density and these mechanisms, as density is often predicted to influence both inter and intraspecific encounters. Results of our study indicate that frequency of intraspecific interactions between deer mice was reduced with increased diversity. Species diversity did not impact average duration of encounters. Density was correlated with absolute, but not relative rates of encounters between deer mice, suggesting that encounters may be influenced by factors other than density. Our study indicates that species diversity influences the dynamics of SNV by reducing encounters between deer mice in a trade-off between intra and interspecific interactions.     

Non-native Species and Rates of Spread: Lessons from the Brackish Baltic Sea

The Baltic Sea, a semi-enclosed brackish water region, has been inoculated by non-indigenous species for centuries. Today, much of its biological diversity is of foreign origin (i.e. xenodiversity), intentionally or unintentionally moved by humans over ecological and geographical barriers. As many as 98 introduced species have been recorded in the Baltic Sea and Kattegat. The role and abundance of much of the unique native brackish water fauna of the Baltic Sea are threatened by these non-indigenous species. The rate of primary introductions into the Baltic has increased since the 1950s; the secondary rate of spread of non-indigenous species within the basin varies from 30–480 km/year. We review here the invasion histories of the brown alga Sargassum muticum (introduced in the early 1990s), the mud snail Potamopyrgus antipodarum (1887), the barnacle Balanus improvisus (1844), the polychaetes Marenzelleria viridis (1985) and Polydora redeki (1963), the cladoceran Cercopagis pengoi (1992) and the mysid shrimp Hemimysis anomala (1962). This revised version was published online in July 2006 with corrections to the Cover Date.     

Structures of the Mitochondrial CDP-DAG Synthase Tam41 Suggest a Potential Lipid Substrate Pathway from Membrane to the Active Site

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Expression Patterns of the Drosophila Neuropeptide CCHamide-2 and Its Receptor May Suggest Hormonal Signaling from the Gut to the Brain

The insect neuropeptides CCHamide-1 and -2 are recently discovered peptides that probably occur in all arthropods. Here, we used immunocytochemistry, in situ hybridization, and quantitative PCR (qPCR), to localize the two peptides in the fruitfly Drosophila melanogaster. We found that CCHamide-1 and -2 were localized in endocrine cells of the midgut of larvae and adult flies. These endocrine cells had the appearance of sensory cells, projecting processes close to or into the gut lumen. In addition, CCHamide-2 was also localized in about forty neurons in the brain hemispheres and ventral nerve cord of larvae. Using qPCR we found high expression of the CCHamide-2 gene in the larval gut and very low expression of its receptor gene, while in the larval brain we found low expression of CCHamide-2 and very high expression of its receptor. These expression patterns suggest the following model: Endocrine CCHamide-2 cells in the gut sense the quality of food components in the gut lumen and transmit this information to the brain by releasing CCHamide-2 into the circulation; subsequently, after binding to its brain receptors, CCHamides-2 induces an altered feeding behavior in the animal and possibly other homeostatic adaptations.     

Osteopathology in Rhinocerotidae from 50 Million Years to the Present

Individual elements of many extinct and extant North American rhinocerotids display osteopathologies, particularly exostoses, abnormal textures, and joint margin porosity, that are commonly associated with localized bone trauma. When we evaluated six extinct rhinocerotid species spanning 50 million years (Ma), we found the incidence of osteopathology increases from 28% of all elements of Eocene Hyrachyus eximius to 65–80% of all elements in more derived species. The only extant species in this study, Diceros bicornis, displayed less osteopathologies (50%) than the more derived extinct taxa. To get a finer-grained picture, we scored each fossil for seven pathological indicators on a scale of 1–4. We estimated the average mass of each taxon using M1-3 length and compared mass to average pathological score for each category. We found that with increasing mass, osteopathology also significantly increases. We then ran a phylogenetically-controlled regression analysis using a time-calibrated phylogeny of our study taxa. Mass estimates were found to significantly covary with abnormal foramen shape and abnormal bone textures. This pattern in osteopathological expression may reflect a part of the complex system of adaptations in the Rhinocerotidae over millions of years, where increased mass, cursoriality, and/or increased life span are selected for, to the detriment of long-term bone health. This work has important implications for the future health of hoofed animals and humans alike.     

Marine Reserves: from Beverton and Holt to the Present

The idea of using marine reserves, where all fishing is banned is not new to fisheries management. It was first formally considered by Beverton and Holt but rejected in favour of approaches such as fleet and gear control. Since that analysis, many fisheries have collapsed worldwide, illustrating the vulnerability of fishery resources and the ineffectiveness of these approaches. Empirical data and modelling suggest that marine reserves would generally increase yields, especially at the high fishing mortality that occurs in most fisheries. However, the most interesting feature of reserves is their ability to provide resilience to overexploitation, thereby reducing the risk of stock collapse. Benefits from reserves come from the increase in biomass and individual size within them, resulting in adult migration and/or larval dispersal that would replenish fishing grounds. The use of marine reserves in managing fisheries necessitates a thorough understanding of critical habitat requirements, fish movement, fish behaviour, the relations between subpopulations and the critical density effect for larval dispersal. When properly designed, and coupled with other management practices, reserves may provide a better insurance against uncertainties in stock assessment, fishing control and management by protecting a part of the population from exploitation. This strategy can be used for both sedentary and migratory species.     

More topics from the tropics: additional thoughts to Mammides et al.

Most studies on tropical conservation questions are conducted by researchers of developed countries from the north. This geographic disconnection was recently criticised by Mammides et al. Here, we reflect on their findings and add further views from scientist’s and journal editor’s perspectives. We argue that journals are, a priori, most strongly interested in research questions and approaches that will likely increase their scientific impact and prestige. This is rarely compatible with publishing articles on questions with restricted global impact or based on single taxa. We question whether small changes in the editorial policy of international conservation journals will considerably improve the geographic diversity in key conservation publications. Rather, thematic scopes of the leading conservation journals should be modified, preferably in close collaboration with leading conservationists from the south. We are convinced that long-term investments in the tropics will create a stronger local scientific community, thus bolstering academic morale, and finally may lead to an increase in the submission and acceptance rate of articles written from scientists from these regions.     

Declining sleep quality among nurses: a population-based four-year longitudinal study on the transition from nursing education to working life

Background

Several studies have established impaired sleep is a common problem among nurses. Overworked, fatigued and stressed nurses are at a higher risk of making mistakes that threaten patient safety as well as their own health. The aim of the present study was to longitudinally monitor the development of sleep quality in nurses, starting from the last semester at the university, with three subsequent annual follow-ups once the nurses had entered working life.

Methodology/Principal Findings

Nationwide, longitudinal questionnaire study of nursing students and newly qualified nurses in Sweden. The results imply a continuous decline in sleep quality among nurses during the three years of follow-up, starting from their last semester of nursing education and continuing for three years into their working life. The most pronounced short-term decline in sleep quality seems to occur in the transition between student life and working life.

Conclusion/Significance

This finding is important since it may affect the quality of care and the health of nurses negatively.     

刺齿虫兆属温州一新种及浙江分种检索表（弹尾纲：长角虫兆科）

记述刺齿虫兆属温州 1 新种:六毛刺齿虫兆Homidia hexaseta sp. nov.,该种的鉴别特征包括体色,下唇具光滑毛L1,头背部顶区具6根大刚毛,胸部第Ⅱ节具p4系列大刚毛,腹部第Ⅲ节中间具a2大刚毛,腹部第Ⅳ节具B6和Ae5-7大刚毛以及端节亚顶端齿远大于顶端齿。同时,本文还给出了浙江省刺齿虫兆属分种检索表。正模:♀,浙江省温州市泰顺县乌岩岭国家自然保护区,采集号C9271-4,2005-Ⅶ-29;副模:5♀♀。其中两头雌性副模标本保存于台州学院生命科学学院,其余标本保存于南京大学生命科学学院。     

A New Species of Chelipoda Macquart,with a Key to the Species from China (Diptera: Empididae)

Chelipoda nigraristata sp. n., a new aquatic dance fly of the subfamily Hemerodromiinae (Diptera, Empididae) is described from China. Relationships with other described species are discussed. A key to the species of the genus Chelipoda from China is presented for the first time.     

A New Species of Dolichocephala,with a Key to the Species from China (Insecta: Diptera,Empididae)

Dolichocephala guangdongensis sp. n., a new aquatic dance fly (Diptera, Empididae), is described from Guangdong province in China. The relationships with its sister species are discussed. A key to the species of the genus Dolichocephala from China is presented.     

单格孢属(丝孢纲)3个新种及中国土壤中单格孢属真菌已知种检索表

报道分离自中国云南、青海、福建3省土壤的单格孢属(Monodictys)3个新种:珠芽状单格孢M.bulbiliformis、黄河单格孢M.huangheensis和厦门单格孢M.xiamenensis,并对其进行了形态描述和讨论。文中提供了中国土壤中单格孢属16个已知种的分种检索表。新种的模式标本(干制培养物)及活菌种保存在山东农业大学植物病理学标本室(HSAUP),等模式标本(干制培养物)保存在中国科学院菌物标本馆(HMAS)。     

Species and serovars of the genus Listeria isolated from different sources in Brazil from 1971 to 1997

Using phenotype techniques, characterization was made to species and serovar of 3,112 strains of Listeria, isolated from different sources of infection such as human (247-7.9%) and animals (239-7.6%), as well as from various routes of infection, including food (2, 330-74.8%) and environmental constituents (296-9.5%), all coming from different regions of the country and collected during the period 1971-1997. The following species were recovered in the cultures analysed: L. monocytogenes (774-24.8%), L. innocua (2, 269-72.9%), L. seeligeri (37-1.1%), L. welshimeri (22-0.7%), L. grayi (9-0.2%), and L. ivanovii (1-0.03%). L. monocytogenes was represented by ten serovars, the most prevalent being 4b (352-11.3%), (1/2)a (162-5.2%), and (1/2)b (148-4.7%). The predominant serovar in L. innocua was 6a (2,093-67.2%). Considerations about laboratory methods for diagnosis and epidemiological aspects are presented on the basis of the results obtained.     

Species variation in the fixation and transfer of nitrogen from legumes to associated grasses

Summary Three legume species (alfalfa, red clover, and birdsfoot trefoil) in combination with five grass species (timothy, bromegrass, red fescue, tall fescue, and orchardgrass) were used to study N transfer in mixtures, using the 15_N dilution technique. The advantage of grass-legume mixtures was apparent. Total herbage and protein yields of grasses in mixtures were higher than those alone, especially at the later cuts. This benefit of mixed cropping is mainly due to N transfer from legumes to associated grasses. N₂-fixation and N transfer by alfalfa rated highest, red clover intermediate, and birdsfoot trefoil lowest. The importance of each pathway of N transfer from legumes appeared to differ between species. Alfalfa and red clover excreted more N than trefoil, while the latter contributed more N from decomposition of dead nodule and root tissue. The greatest advantage from a grass-legume mixture, with respect to the utilization of N released from the legume, varied with early maturing tall fescue (Kentucky 31), orchardgrass (Juno), and bromegrass (Tempo), to intermediate timothy (Climax), and least with late maturing red fescue (Carlawn). Contribution no. 817 of the Ottawa Research Station.     

中国沼野蝇属一新种附该属的种检索表及属征(双翅目:麻蝇科)

沼野蝇属Goniophyto Townsend, 1927已记载有6种,其中2种分布于中国。本文描述了在上海蝇类调查中发现的该属1新种G. shanghaiensis的两性特征,并附该属的种检索表及属征的修订。模式标本存于上海出入境检验检疫局媒介生物实验室。上海沼野蝇 Goniophyto shanghaiensis,新种(图 1~6) 本种♂额角几为直角与九州沼野蝇G. horri Kurahashi et Suenaga, 1994近缘;但胫节棕色而非黑色,侧尾叶后缘端半呈直角形明显内凹而非稍微内凹,阳茎腹方有一对宽的近端侧突而非仅呈细长管状。正模:♂,上海南汇区,2005-Ⅺ-25,邓耀华、陈之梓采;副模:5♂♂10♀♀,上海崇明岛,2005-Ⅵ-26,邓耀华、陈之梓采。     

Interspecific Variation in the Reproductive Response of Acacia Species to Protection from Large Mammalian Herbivores

We quantified the fruit set of four Acacia spp. inside and outside of long-term experimental exclosures in order to examine the fitness consequences of herbivory by large mammals. We found a considerable interspecific variation in the reproductive fitness costs of herbivory in four African Acacia spp. Acacia nilotica and A. brevispica respond to protection from large mammalian herbivores by greatly increasing their seed set. In contrast, there was little or no increase in seed set in A. mellifera and A. etbaica . The reasons for these differences are not known, but may be related to armament morphologies.     

Enhancement of Bacillus thuringiensis Toxicity to Lepidopterous Species with the Enhancin from Trichoplusia ni Granulovirus

The enhancin from the Trichoplusia ni (Hübner) granulovirus (TnGV) is a 104-kDa viral protein that can significantly increase the virulence of several baculoviruses. Enhancin can destroy the structural integrity of the peritrophic membrane (PM) of lepidopterous larvae, resulting in more efficient penetration of the PM by virions and avoidance of inactivation by larval midgut factors. In this study we demonstrate that TnGV enhancin can also enhance toxicity of Bacillus thuringiensis (Berliner) (Bt) to several noctuid species. Addition of enhancin significantly increased the toxicity of Dipel, a commercial Bt formulation, to six species (T. ni, Helicoverpa zea (Boddie), Heliothis virescens (Fabricius), Spodoptera exigua (Hübner), Pseudoplusia includens (Walker), and Anticarsia gemmatalis (Hübner)). Furthermore, the effectiveness of four commercial Bt-based products (Cutlass, Javelin, Biobit, and Dipel) against T. ni was enhanced three- to sixfold by adding purified enhancin. We hypothesize that the PM of larvae can impede the movement of the BT toxin protein to the midgut brush border and that enhancin can increase the toxicity by affecting the permeability of the PM.