Muskrat (Ondatra zibethicus) decline after the expansion of American mink (Neovison vison) in Poland

Field survey data in Central Poland revealed that the proportion of sites inhabited by muskrats decreased from 44% to 7% over one decade. This corresponded to the decline in hunting bags of muskrat over the whole of Poland. The largest hunting harvest of muskrat was recorded in 1987/1988 (66,416 individuals), the smallest in 2007/2008 (4,567 individuals). The decline in hunting bags occurred in all regions analysed; however, it was most rapid in the north and north-east. Before the expansion of mink, which started in northern Poland at the beginning of the 1980s, muskrat densities in particular regions depended on the availability of aquatic habitats. A comparison of hunting bags of muskrat and American mink in years 2002–2008 indicated a significant negative correlation between the numbers of these two species harvested in seven regions of Poland. The negative correlation between numbers of muskrat and mink suggests that mink predation is one of the most important factors in the decline of the muskrat population in Poland.     

麝鼠前列腺在繁殖期和非繁殖期转录组差异分析

麝鼠(Ondatra zibethicus L.)是季节性繁殖动物。成年雄性麝鼠在尿生殖孔上方肌肉与背皮之间有一对香腺,在繁殖期能分泌麝鼠香。与其他鼠类相比,麝鼠在繁殖期时前列腺—精囊腺组织极其发达。研究发现,经腹腔注射麝鼠香后,能够明显促进雄性小鼠的前列腺—精囊腺发育,表明两者之间可能存在一定的相关性。本研究利用RNA-seq技术对麝鼠繁殖期和非繁殖期的前列腺样品进行了转录组测序,对差异表达的基因进行GO分析和KEGG通路分析。结果显示,共筛选出1629个显著差异表达基因,涉及多种信号转导和能量代谢相关基因,其中OBP2、Bcl-2家族和肿瘤坏死因子受体超家族成员的差异表达提示麝鼠前列腺发育受多种机制调控,由香腺分泌的麝鼠香可能参与了前列腺的发育调节。     

Sarcoma of possible nerve sheath origin in a captive muskrat

A captive adult female muskrat (Ondatra zibethicus) was found dead without previous signs of disease. At necropsy, abdominal organs were infiltrated with a poorly demarcated, soft, tan tissue. Microscopically this tissue was composed of neoplastic cells assuming two distinct growth characteristics consistent with Antoni A and B patterns. Ultrastructurally, the neoplastic cells were pleomorphic, lacked junctional devices, had abundant mitochondria and ergastoplasm, and frequently were closely associated with extracellular collagen. Immunocytochemical examination of tumor cells demonstrated sporadic expression of neuron specific enolase. Microscopic tumor metastases to the myocardium, ascending aorta, lungs and visceral pleura were present. This is the first report of a sarcoma compatible with a malignant peripheral nerve sheath tumor in a muskrat.     

白术连作根际土壤的理化性质及微生物区系变化

对不同种植年限白术(Atractylodes macrocephala Koidz.)根际土壤的部分理化指标、酶活性和微生物区系进行了测定和比较。结果表明:随白术种植年限的增加(0、1和2 a),根际土壤pH值显著下降(P<0.05),根际土壤中有机质和全氮含量呈先升高后降低趋势,速效钾含量则逐渐升高,而有效磷含量和C/N比小幅波动,总体上不同种植年限根际土壤的这些指标差异不显著;根际土壤中有效铁、有效铝和交换性锰含量显著或极显著(P<0.01)增加,且较对照(未种植白术的土壤)分别增加了127.51%、18.38%和106.83%,但有效铅含量变化幅度较小;2年生白术根际土壤中过氧化氢酶、脲酶和蛋白酶活性显著低于对照;2年生白术根际土壤中细菌和放线菌数量及微生物总量较1年生白术根际土壤显著下降,真菌数量则显著上升。结果显示:土壤酸化严重、金属离子大量积累、主要酶活性失调以及微生物区系改变可能是白术连作障碍的潜在原因。     

Discordance between phylogenetics and coalescent-based divergence modelling: exploring phylogeographic patterns of speciation in the Carex macrocephala species complex

We fit a molecular data set, consisting of the rpL16 cpDNA marker and eight microsatellite loci, to the isolation-with-migration model as implemented in IM a to test a well-supported phylogenetic hypothesis of relationships within the Carex macrocephala species complex (Cyperaceae). The phylogenetic hypothesis suggests C. macrocephala from North America is reciprocally monophyletic and is sister to a reciprocally monophyletic clade of C. kobomugi . The North American C. macrocephala and C. kobomugi clade form a sister clade with a lineage of Asian C. macrocephala , thereby forming a paraphyletic C. macrocephala species. Not only does the phylogenetic hypothesis suggest C. macrocephala is paraphyletic, but it also suggests that the two lineages which share a partially overlapping distribution, Asian C. macrocephala and C. kobomugi , are not the most closely related. To test these relationships, we used coalescent-based population genetic models to infer divergence time for each lineage pair within the species complex. The coalescent-based models account for the stochastic forces which drive population divergence, and can account for the lineage sorting that occurs prior to lineage divergence. A drawback to phylogenetic-based phylogeographical analyses is that they do not account for stochastic lineage sorting that occurs between gene divergence and lineage divergence. By comparing the relative divergence time of the three main lineages within this group, Asian C. macrocephala , North American C. macrocephala , and C. kobomugi , we concluded that the phylogenetic hypothesis is incorrect, and the divergence between these lineages occurred during the Late Pleistocene epoch.     

侵染白术的大豆花叶病毒的全基因序列测定及分析

大豆花叶病毒(soybean mosaic virus,SMV)是影响大豆产量与质量的重要病原体,且自然寄主范围窄。本研究对疑似感病白术叶片进行非序列依赖性扩增(sequence-independent amplification,SIA)检测,结果表明,感病白术为SMV侵染,并命名为SMV-Am。为明确其基因组结构特征及系统进化关系,本研究利用双链RNA(double-stranded RNA,dsRNA)提取、RT-PCR及RACE技术对其进行全基因组扩增,并进行生物信息学分析。结果表明,SMV-Am基因组全长9 587 nt,具有显著的马铃薯Y病毒属(Potyvirus)基因组结构特征;核苷酸与氨基酸序列相似性分析表明,SMV-Am与来自中国的SMV-Liaoning分离物相似性最高,核苷酸与氨基酸序列相似性分别为96.57%和98.86%;系统进化分析也显示与SMV-Liaoning分离物亲缘关系最近;对SMV-Am蛋白序列进一步分析发现,存在与功能位点相关的氨基酸突变,经I-TASSER和PyMOL软件进行蛋白建模分析,发现SMV-Am的P1、HC-Pro、P3、6K2、NIa-Pro、NIb蛋白结构均发生不同程度的变化,且P1蛋白最明显;重组分析结果显示,在SMV-Am基因组的6 560~8 950 nt位置存在重组事件,其主要亲本和次要亲本分别为SMV-XFQ012(GenBank登录号:KP710875.1)和SMV-pCB301-SC15(GenBank登录号:MH919386.1)。这是SMV侵染白术的首次报道,研究结果有望为防范SMV病害在白术上爆发流行以及防治提供科学依据。     

施磷水平对接种AM真菌白术植株生长和生理特征的影响

以非灭菌土为生长基质,采用盆栽实验研究了不同施磷水平下接种摩西球囊霉(Glomus mosseae)对白术生长和生理特征的影响.结果表明,摩西球囊霉能够与白术形成良好的共生关系,在0～0.4 g P/kg土水平时,接种摩西球囊霉可显著提高白术根系菌根侵染率,并以0.05 g P/kg土水平时侵染率最大,磷水平继续提高则菌根侵染率反而降低;接种摩西球囊霉对白术地下部的影响效果尤为明显,其根长、株高、地下部干重均在0.1 g P/kg水平时达到最大值;适量施磷条件下,接种摩西球囊霉可显著提高植株可溶性糖和可溶性蛋白含量,有效增强保护酶SOD、POD和CAT活性.研究发现,当施磷量为0.05～0.1 g/kg土时,摩西球囊霉接种效果最佳,对白术的生长最为有利.     

Immunolocalization of androgen receptor, aromatase cytochrome P450, estrogen receptor alpha and estrogen receptor beta proteins during the breeding season in scent glands of muskrats (Ondatra zibethicus)

Aromatase cytochrome P450 (P450arom) is an enzyme that catalyzes the conversion of androgen to estrogen. Expression of P450arom in extra-gonadal sites and locally-synthesized estrogen play an important role in physiological conditions. The purpose of this study was to investigate the cellular immunolocalization of androgen receptor (AR), P450arom, estrogen receptor alpha (ERa) and estrogen receptor beta (ERβ) in muskrat scent glands during the breeding season. Histological observation and immunohistochemistry of AR, P450arom, ERa and ERβ were performed in the muskrat scent glands. In addition, total proteins were extracted from scent glandular tissues in the breeding season and were used for Western blotting analysis for AR, P450arom, ERα and ERβ. Histologically, glandular cells, interstitial cells, epithelial cells of the excretory duct and the excretory tubules were identified in the muskrat scent glands during the breeding season. AR was only observed in glandular cells of scent glands; P450arom was expressed in glandular cells and epithelial cells of the excretory duct; ERα was found in glandular cells, interstitial cells and epithelial cells of the excretory duct, whereas ERβ was present in glandular cells and epithelial cells of the excretory duct. Also, the positive signals of AR, P450arom, ERα and ERβ by Western blotting were all observed in scent glandular tissues. These results suggested that the scent gland is the target organ of androgens and estrogens, and that estrogens may play an important autocrine or paracrine role in glandular function of the muskrats.     

Description of Paranoplocephala etholeni n. sp. (Cestoda: Anoplocephalidae) in the meadow vole Microtus pennsylvanicus,with a synopsis of Paranoplocephala s. l. in holarctic rodents

Paranoplocephala etholeni n. sp., parasitizing the meadow vole Microtus pennsylvanicus in Alaska and Wisconsin, USA, is described. Paranoplocephala etholeni is morphologically most closely related to the Nearctic Paranoplocephala ondatrae (Rausch, 1948). Available data suggest that P. etholeni is a host-specific, locally rare species that may have a wide but sporadic geographical distribution in North America. The finding of P. ondatrae-like cestodes in Microtus spp. suggests that this poorly known species may actually be a parasite of voles rather than muskrat (type host). A tabular synopsis of all the known species of Paranoplocephala s. l. in the Holarctic region with their main morphological features is presented.     

Changes in monogenean and copepod infestation on captive Acanthopagrus australis (Sparidae)

Infection levels by 17 species of ectoparasite on 491 yellowfin bream collected throughout 1990 from Moreton Bay, S.E. Queensland were compared to infections on 82 bream collected during the same period from a captive population in a large pond at Sea World, Gold Coast, Queensland. There was a significant increase in prevalence and/or intensity of monogeneans Lamellodiscus acanthopagri and Polylabroides multispinosus , but a decrease in the monogenean Anoplodiscus australis and the copepods Ergasilus australiensis, Lernanthropus atrox, Bomolochus stocki and Alella macrotrachelus on captive fish. Twenty-eight bream collected from the pond during autumn were placed in an experimental 1 m³ cage within the pond for 4–6 weeks. Compared to the baseline data for the pond, the caged fish showed increased prevalences of the monogeneans Lamellodiscus acanthopagri, L. squamosus, L. major and Haliotrema spariensis , and increased intensities of L. squamosus, Allomurraytrema robustum and P. multispinosus. The copepod Caligus epidemicus dropped off in preservative, but its abundance (average number per fish) was significantly higher on caged fish than on pond or wild fish. Increased infection levels by L. acanthopagri and A. robustum were due in part to autoinfection. The large skin area promoted large populations of C. epidemicus.     

Paranoplocephala maseri n. sp. (Cestoda,Anoplocephalidae), a parasite of sagebrush voles Lemmiscus curtatus (Rodentia) in the USA

Paranoplocephala maseri n. sp. is described from Lemmiscus curtatus (Cope) in the USA. The new species is related to Paranoplocephala omphalodes (Hermann, 1783), P. caucasica (Kirschenblat, 1938), P. kirbyi Voge 1948, P. microti (Hansen, 1947) and P. macrocephala (Douthitt, 1915) sensu Genov et al. (1996). P. maseri n. sp. differs from P. omphalodes in the position of the genital pores, testes and cirrus-sac; from P. caucasica, in which there is an unarmed cirrus, in both the distribution and larger number of testes; from P. kirbyi in the distribution of the testes, the position of the genital pores and egg dimensions; from P. microti in the distribution and smaller number of testes, the smaller egg dimensions and the position of the genital pores; and from P. macrocephala in the position of genital pores and cirrus-sac.     

Spatial variation in mink and muskrat interactions in Canada

We investigated the spatial attributes of mink ( Mustela vison ) and muskrat ( Ondatra zibethicus ) interactions in Canada using 160 geographically paired historic time series of mink ( n =80) and muskrat ( n =80) harvest data obtained from Hudson's Bay Co. Archives. All series were 25 years in length (1925–1949) and were distributed primarily throughout five ecozones. We used autoregressive models and cross-correlation analysis to characterize the interactions between mink and muskrat. Model selection results did not differ among ecozones, and indicated that a predator-prey autoregressive model incorporating a delayed density-dependent term best described both the mink and muskrat harvest time series. Subsequent analysis of autoregressive coefficients and estimated lags indicated that mink and muskrat interactions vary throughout Canada. In western Canada, the trophic interactions appear to be strong, and mink population cycles lag behind muskrats 2–3 years. In central Canada, mink harvests lagged behind muskrats 1 year, and mink and muskrat interactions in central Canada, with the exception of the Hudson Plains ecozone, were intermediate. In eastern Canada, the trophic interactions appeared weakest, and there were no distinct time lags between mink and muskrat. Stronger interactions in western Canada may be a result of decreased prey diversity, forcing mink to specialize more on muskrats, whereas comparatively stronger perturbations stemming from other trophic interactions may alter the estimated interaction between mink and muskrat in eastern Canada.     

Immunohistochemical evidence: testicular and scented glandular androgen synthesis in muskrats (Ondatra zibethicus) during the breeding season

In order to elucidate the relationship between androgens and the function of the muskrat (Ondatra zibethicus) scented glands during the breeding season, we investigated immunolocalization of steroidogenic enzymes P450scc, 3βHSD and P450c17 in the muskrat testes and scented glands. Nine adult muskrats were obtained in March (n=3), May (n=3) and July (n=3) 2010. Steroidogenic enzymes were immunolocalized using polyclonal antisera raised against bovine adrenal P450scc, human placental 3βHSD and porcine testicular P450c17. Histologically, all types of spermatogenic cells including mature-phase spermatozoa in seminiferous tubules were observed in all testes. Glandular cells, interstitial cells, epithelial cells and excretory tubules were identified in scented glands during the breeding season. P450scc, 3βHSD and P450c17 were only identified in Leydig cells during the breeding season; P450scc and P450c17 were observed in glandular cells of scented glands, however, 3βHSD was not found in scented glands during the breeding season. These novel findings provide the first evidence showing that scented glands of the muskrats are capable of locally synthesizing androgens and androgens acting via an endocrine, autocrine or paracrine manner may play an important role in scented gland function during the breeding season.     

A molecular phylogeny of New Zealand's Petroica (Aves: Petroicidae) species based on mitochondrial DNA sequences

The New Zealand robin (Petroica australis), tomtit (P. macrocephala), and Chatham Island black robin (P. traversi) are members of the Petroicidae family of Australo-Papuan robins, found throughout Australasia and the western Pacific. In the nearly 200 years since the New Zealand members of Petroicidae were first described, the division of species, subspecies, and even genera has undergone many changes. In this study, we investigate whether molecular phylogenies based on mitochondrial DNA sequences support current taxonomic classifications based on morphology. Petroica traversi, P. australis, and P. macrocephala form distinct clades in phylogenetic trees constructed from Cytochrome b and control region sequences, however the position of the black robin is at odds with the morphological and behavioral data. The black robin does not appear to be a derivative of the New Zealand robin, instead it groups strongly with the tomtit, indicating that lineage sorting and/or introgressive hybridization may have occurred. There is some evidence to support the hypothesis that two invasions of Petroica from Australia have occurred, however additional data from Australian Petroica taxa are required to confirm this. Control region sequences confirm a deep split between the North and South Island P. australis lineages, but suggest a recent radiation of P. macrocephala.     

Presence of Giardia spp. and absence of Salmonella spp. in New Jersey muskrats (Ondatra zibethicus)

Of 220 muskrat fecal specimens collected from 12 sites in southwestern New Jersey, 154 (70%) were found to contain cysts of the protozoan parasite Giardia spp. Cysts from selected muskrat fecal specimens infected Mongolian gerbils, but attempts to cultivate trophozoites removed from these gerbils were unsuccessful. Salmonella spp. were not detected in any of the muskrat fecal specimens.     

Body mass and correlated ecological variables in the North American muskrat lineage: evolutionary rates and the tradeoff of large size and speciation potential

This study tracks evolutionary change in body mass (W) and correlated ecological variables over the 3.75 million year history of the North American muskrat (Ondatra zibethicus). A new model is presented suggesting muskrat body mass has been in equilibrium for most of its history. Four pulses of pronounced size increase are correlated with glacial dynamics and volcanic events. Ranges of evolutionary rates in darwins and a new metric based on percent change in W document episodic size change. Proportional size change is independent of interval length, with a background range attributed to natural selection ≤25–30%. In increasing body mass by a factor of ten to about 1 kg mass-specific metabolism was halved, home range quadrupled, population density decreased fourfold, and average biomass more than doubled. Estimates of species diversity in ancient cotton rats (Sigmodon) and muskrats are calculated from a function derived from the correlation of numbers of North American rodent species and mean W. The phyletic mode of muskrat body size increase is explained as a combination of large body size reducing speciation coupled with an aquatic lifestyle. To the ecological consequences of large size in evolving clades (Cope’s rule) we can now add reduced speciation potential.     

Presence of Giardia spp. and absence of Salmonella spp. in New Jersey muskrats (Ondatra zibethicus).

Of 220 muskrat fecal specimens collected from 12 sites in southwestern New Jersey, 154 (70%) were found to contain cysts of the protozoan parasite Giardia spp. Cysts from selected muskrat fecal specimens infected Mongolian gerbils, but attempts to cultivate trophozoites removed from these gerbils were unsuccessful. Salmonella spp. were not detected in any of the muskrat fecal specimens.     

Calcium transport mechanisms in muskrat and rat hearts

Mammalian hearts experience calcium overload during extreme and prolonged hypoxia and the calcium overload may lead to enzyme activation and cell death. Several calcium transport systems were examined in muskrat hearts and compared to those found in rat hearts to determine if there is a species difference that might be related to the muskrats' superior ability to survive hypoxia. Radiolabeled nitredendipine binding was determined in rat and muskrat hearts to estimate the density of voltage gated calcium channels in surface membranes. There were no species differences. Calcium release channel density in the sarcoplasmic reticulum was estimated by the determination of radiolabeled ryanodine binding in muskrat and rat heart SR membranes. No differences were revealed between species. The SR uptake of calcium was measured in SR membranes from the hearts of the two species. No differences were found in the B(max) values, however, the muskrat SR membranes did have a slightly lower K(m) value. There were large species differences in Na(+)/Ca(2+) exchange in SL membranes with the muskrat heart having approximately 3.5 times the transport capacity of rat SL membranes. During hypoxic conditions in which there is extensive ATP depletion leading to [Na(+)](i) accumulation and discharge of cellular membrane potential, the Na(+)/Ca(2+) exchanger may operate in the reverse mode and import calcium into the cell and accelerate hypoxic damage. Prior to reaching this state a robust Na(+)/Ca(2+) exchange would facilitate the maintenance of normal diastolic calcium levels and calcium cycling. Muskrats hearts are hypoxia tolerant by virtue of their ability to reduce metabolic demand and generate ATP anaerobically thus, maintaining a favorable ATP balance. Therefore, the relative overexpression of Na(+)/Ca(2+) exchangers in muskrat hearts may be beneficial in the preservation of contractile function and calcium homeostasis in this freshwater diving mammal.     

安徽白术资源调查

目的：了解安徽省内白术资源情况。方法：实地调查。结果：安徽省内有野生白术品种“舒州术”、“歙州术”和“祁术”,但都濒临灭绝;皖南山区和亳州地区有栽培白术并作为药材商品供应市场。结论：野生白术资源濒危,殛待保护;皖南栽培白术产量少,分散;亳州栽培白术面积大,产量高。发展白术栽培,有利于地方经济的发展。