Are local plague endemicity and ecological characteristics of vectors and reservoirs related? A case study in north-east Tanzania

The pattern of plague endemicity in Tanzania is characterized by continuous re-appearance of the disease in some locations,while in other neighbouring villages the disease has never or seldom been observed.To understand the reasons for this pattern,we studied small mammal and flea species composition,diversity and relative abundances in two plague-endemic and two plague-free locations.We asked(a)whether fleas more abundant in plague-endemic locations differ in their characteristic abundance and the degree of their host specificity from fleas more abundant in plague-free locations and(b)whether hosts most abundant in plague-endemic locations differ in the diversity of their flea assemblages from hosts most abundant in plague-free locations.We characterized(a)each host species by species richness and degree of taxonomic relatedness of its flea assemblages and(b)each flea species by its mean abundance and size,and degree of taxonomic relatedness of its host spectrum and compared their relative abundances between locations.No significant difference between plague-endemic and plague-free locations in either host density or any variable related to flea abundance or diversity was found.However,there was marginally significant effect of taxonomic distinctness of a flea assemblage harboured by a host on its probability to be more abundant in either plague-endemic or plague-free locations.Furthermore,hosts more abundant in plague-endemic locations tended to harbour closely-related fleas.Finally,while opportunistic and specialist fleas were equally distributed in both sets of locations,fleas exploiting distantly-related hosts were found mainly in plague-free locations during the rainy season.We suggest that the observed patterns might arise due to seasonal and spatial differences in local microclimatic conditions and landscape connectivity.

Human seroreactivity against Bartonella species in the Democratic Republic of Congo

Objective:To assess the presence and identity of Bartonella species in a pool of human blood samples from DRC Congo.Methods:Blood(±120μL) was collected anonymously from Congolese patients and placed on calibrated filter papers.Bartonella serology determination was performed using an indirect immun of luorescence assay(IFA) against six specific Bartonella antigens and Coxiella burnetii(C.burnetii) antigen.The end cut- of f value for Bartonella sp.was a titre greater than 1200.Results:None of the patients was positive for Bartonella elizabethae, Bartonella vinsonii subsp.vinsonii or Bartonella vinsonii subsp.arupensis nor for C.burnetti, but 4.5%of the 1SS samples were positive for either Bartonella henselae,Bartonella quintana, or Bartonella clarridgeiae.Conclusions:This preliminary study presents the first report of Bartonella species in the DR Congo and the first report of antibodies to Bartonella clarridgeiae in an African human population.Although few experimental trials have established the link between fleas and Bartonella transmission,the repeated detection of similar Bartonella species in fleas and humans in several countries suggests that Bartonellosis could be another flea-borne disease which specific reservoirs are still unknown.

Effects of forest management on biomass stocks in Romanian beech forests

Background: Forest management aims at obtaining a sustainable production of wood to be harvested to generate products or energy. However, the quantitative influence of forest management and of removals by harvest on biomass stocks has rarely been analysed on a large scale based on measurements. Two hypotheses prevail: management induces a reduction of wood stocks due to cuttings, versus no impact because of increased growth of the remaining trees. Using data collected for 2840 permanent plots across Romania from the National Forest Inventory representing^2.5 Mha, we have tested to what extent different management types and treatments can influence the biomass stock and productivity of beech forests, and attempt to quantify these effects both on the short and long terms. Three main types of beech forest management are implemented in Romania with specific objectives: intensive wood production in production forests, protection of ecosystem services (e.g. watersheds, avalanche protection) in protection forests, and protection of the forest and its biodiversity in protected forests. Production forests encompass two treatments differing according to the stand regeneration method: the age class rotation management and the group shelterwood management. Results: We show that forest management had little influence on the biomass stocks at a given stand age. The highest stocks at stand age 100 were observed in production forests (the most intensively managed forests). Consequences of early cuttings were very short-termed because the increase in tree growth rapidly compensated for tree cuttings. The cumulated biomass of production forests exceeded that of protected and protection forests. Regarding the treatment, the group shelterwood forests had a markedly higher production over a full rotation period. The total amount of deadwood was primarily driven by the amount of standing deadwood, and no management effect was detected. Conclusions: Given the relatively low-intensity management in Romania, forest management had no negative impact on wood stocks in beech forests biomass stocks at large scale. Stand productivity was very similar among management types or treatments. However cumulated biomass in production forests was higher than in protection or protected forests, and differed markedly according to treatments with a higher cumulated biomass in shelterwood forests.

瘤棘砂壳虫(肉足亚门:根足总纲)壳体元素组成(英文)

利用X射线能谱仪对采自中国湖北省木兰湖的瘤棘砂壳虫 (Difflugiatuberspinifera)壳体元素组成进行分析 ,结果发现 :构成壳体的化学元素主要为Si,其次是Ca和Al ,还有微量K、Na、Cl、Fe、Mg、S和P。分析表明瘤棘砂壳虫壳体化学元素的构成介于海洋和土壤有壳肉足虫之间。

伴共济失调但无肌肉受累的神经变性疾病的POLG突变

Objective: To identify POLG mutations in patients with sensory ataxia and CNS features. Methods: The authors characterized clinical, laboratory, and molecular genetic features in eight patients from five European families. The authors con ducted sequencing of coding exons of POLG, C10orf2 (Twinkle), and ANT1 and analy zed muscle mitochondrial DNA (mtDNA), including Southern blot analysis and long range PCR. Results: Ataxia occurred in combination with various CNS features,i ncluding myoclonus, epilepsy, cognitive decline, nystagmus, dysarthria, thalamic and cerebellar white matter lesions onMRI, and neuronal loss in discrete gray n uclei on autopsy. Gastrointestinal dysmotility, weight loss, cardiomyopathy, and valproate induced hepatotoxicity occurred less frequently. Two patients died w ithout preceding signs of progressive external ophthalmoplegia. In muscle, typic al findings of mitochondrial disease, such as ragged red fibers and Southern blo t mtDNA abnormalities, were absent. POLG mutations were present in eight patient s, including two isolated cases, and one Finnish and two unrelated Belgian famil ies contained in total six patients. All POLG mutations were recessive, occurrin g in a homozygous state in seven patients and in a compound heterozygous state i n one patient. The novel W748S mutation was identified in five patients from thr ee unrelated families. Conclusions: The clinical spectrum of recessive POLG muta tions is expanded by sensory ataxic neuropathy, combined with variable features of involvement of CNS and other organs. Progressive external ophthalmoplegia, my opathy, ragged red fibers, and Southern blot abnormalities of muscle mitochondri al DNA also are not mandatory features associated with POLG mutations.

Fluxes of water,sediments,and biogeochemical compounds in salt marshes

Tidal oscillations systematically flood salt marshes,transporting water,sediments,organic matter,and biogeochemical elements such as silica.Here we present a review of recent studies on these fluxes and their effects on both ecosystem functioning and morphological evolution of salt marshes.We reexamine a simplified model for the computation of water fluxes in salt marshes that captures the asymmetry in discharge between flood and ebb.We discuss the role of storm conditions on sediment fluxes both in tidal channels and on the marsh platform.We present recent methods and field instruments for the measurement of fluxes of organic matter.These methods will provide long-term data sets with fine temporal resolution that will help scientists to close the carbon budget in salt marshes.Finally,the main processes controlling fluxes of biogenic and dissolved silica in salt marshes are explained,with particular emphasis on the uptake by marsh macrophytes and diatoms.