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.     

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.     

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)。     

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.     

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.     

A Third Species of Hemilecanium Newstead (Hemiptera: Coccoidea: Coccidae) from the New World, with Keys to Species in the Genus

A new species of Hemilecanium Newstead, Hemilecanium guanabana Kondo & Hodgson n. sp., is described and illustrated based on the adult female, adult male and first instar. The specimens were collected in the municipality of Palmira, state of Valle del Cauca, Colombia, on soursop, Annona muricata (Annonaceae). Updated identification keys are provided for the adult females of all 28 species of the genus Hemilecanium, and for known adult males and first instars. An updated list of the 23 species of soft scales (Coccidae) known from soursop worldwide is included.     

Rates and Factors Associated with Major Modifications to First-Line Combination Antiretroviral Therapy: Results from the Asia-Pacific Region

Background

In the Asia-Pacific region many countries have adopted the WHO’s public health approach to HIV care and treatment. We performed exploratory analyses of the factors associated with first major modification to first-line combination antiretroviral therapy (ART) in resource-rich and resource-limited countries in the region.

Methods

We selected treatment naive HIV-positive adults from the Australian HIV Observational Database (AHOD) and the TREAT Asia HIV Observational Database (TAHOD). We dichotomised each country’s per capita income into high/upper-middle (T-H) and lower-middle/low (T-L). Survival methods stratified by income were used to explore time to first major modification of first-line ART and associated factors. We defined a treatment modification as either initiation of a new class of antiretroviral (ARV) or a substitution of two or more ARV agents from within the same ARV class.

Results

A total of 4250 patients had 961 major modifications to first-line ART in the first five years of therapy. The cumulative incidence (95% CI) of treatment modification was 0.48 (0.44–0.52), 0.33 (0.30–0.36) and 0.21 (0.18–0.23) for AHOD, T-H and T-L respectively. We found no strong associations between typical patient characteristic factors and rates of treatment modification. In AHOD, relative to sites that monitor twice-yearly (both CD4 and HIV RNA-VL), quarterly monitoring corresponded with a doubling of the rate of treatment modifications. In T-H, relative to sites that monitor once-yearly (both CD4 and HIV RNA-VL), monitoring twice-yearly corresponded to a 1.8 factor increase in treatment modifications. In T-L, no sites on average monitored both CD4 & HIV RNA-VL concurrently once-yearly. We found no differences in rates of modifications for once- or twice-yearly CD4 count monitoring.

Conclusions

Low-income countries tended to have lower rates of major modifications made to first-line ART compared to higher-income countries. In higher-income countries, an increased rate of RNA-VL monitoring was associated with increased modifications to first-line ART.     

Two New Species of Zeugmatothrips Priesner, 1925 (Thysanoptera: Phlaeothripidae: Idolothripinae) from Costa Rica with a Key to the Species

Two new species of Zeugmatothrips are described from Costa Rica. The species Z. verae n. sp. can be distinguished by the wide abdominal segments II–V and body length. On the other hand, Z. gerardoi n. sp. is characteristic by the length of the mid-dorsal setae on the head and the seta on antennal segment V. The key of Mound & Palmer modified for eighteen species is presented.     

More mog genes that influence the switch from spermatogenesis to oogenesis in the hermaphrodite germ line of Caenorhabditis elegans

The Caenorhobditis elegans XX animal possesses a hermaphrodite germ line, producing first sperm, then oocytes. In this paper, we report the genetic identification of five genes, mog-2, mog-3, mog-4, mog-5, and mog-6, that influence the hermaphrodite switch from sper-matogenesis to oogenesis. In mcg-2-mog-6 mutants, spermatogenesis continues past the time at which hermaphrodites normally switch into oogenesis and no oocytes are observed. Therefore, in these mutants, germ cells are transformed from a female fate (oocyte) to a male fate (sperm). The fem-3 gene is one of five genes that acts at the end of the germline sex determination pathway to direct spermatogenesis. Analyses of mog;fem-3 double mutants suggest that the mog-2-mog-6 genes act before fem-3; thus these genes may be in a position to negatively regulate fem-3 or one of the other terminal regulators of germline sex determination. Double mutants of fem-3 and any one of the mog mutations make oocytes. Using these double mutants, we show that oocytes from any mog;fem-3 double mutant are defective in their ability to support embryogenesis. This maternal effect lethality indicates that each of the mog genes is required for embryogenesis. The two defects in mog-2-mog-6 mutants are similar to those of mog-1: all six mog genes eliminate the sperm/oocyte switch in hermaphrodites and cause maternal effect lethality. We propose that the mog-2-mog-6 mutations identify genes that act with mog-1 to effect the sperm/oocyte switch. We further speculate that the mog-1-mog-6 mutations all interfere with translational controls of fem-3 and other maternal mRNAs. © 1993 Wiley-Liss, Inc.     

New Species and New Records of Dexosarcophaga Townsend (Diptera: Sarcophagidae) from Brazil with a Key to Species of the Subgenus Bezzisca

Dexosarcophaga tupinamba n. sp. is described based on male specimens from the Brazilian states of Pará and Maranhão; Dexosarcophaga bermudezi Silva & Mello-Patiu is newly recorded from Pará and South America; and Dexosarcophaga avispaensis Mello is newly recorded from Pará (new to Brazil). The Brazilian species Dexosarcophaga limitata (Lopes) and Dexosarcophaga pusilla (Lopes) are both recorded from Pará, which are new records from the Brazilian Amazon, Dexosarcophaga aurifacies (Lopes) is newly recorded from the state of Alagoas and Dexosarcophaga carvalhoi (Lopes) is newly recorded from the states of Mato Grosso, Maranhão, and Pará. A key to the identification of males of the subgenus Bezzisca is provided.     

中国裸伞属已知种的分布及1个大陆新记录种

对我国22个省区的裸伞属(GymnopilusP.Karst.)27个已知名称进行了整理和修订,并描述了1个中国大陆新记录种———藏花黄褶裸伞[Gymnopilus crociphyllus(Cooke&Massee)Pegler]。