Spatial and temporal overlap of caracal and serval in Serengeti National Park,Tanzania

Understanding activity and habitat use are important for identifying mechanisms facilitating species co-occurrence. We studied habitat use and activity patterns of caracals (Caracal caracal) and servals (Leptailurus serval), primarily nocturnal, mid-sized felids that prey extensively on small mammals and co-occur in portions of sub-Saharan Africa. Spatial and temporal patterns of segregation were investigated in a 1,085-km² area of Serengeti National Park, Tanzania from 2010–2012. We used occupancy analysis to quantify habitat use and kernel density estimators and Mardia–Watson–Wheleer tests to analyse activity patterns. We found evidence for habitat divergence but high temporal overlap between species. Servals selected for grassland and avoided shrubland and wooded grassland. In contrast, the findings showed that caracals avoided grassland and woodland–shrubland; however, 73% of caracals were detected in wooded grassland. Overall, caracals and servals co-occurred independently, Species Interaction Factor, (phi = 1). This indicates that differential use of habitats in part facilitated coexistence of caracals and servals. Proper management of the declining grasslands including other habitats are recommended to facilitate continued coexistence. Additional studies, including feeding ecology, would be important to further understand mechanisms facilitating coexistence between caracals and servals.     

海南尖峰岭国家级自然保护区雨季鱼类群落结构特征研究

为了了解海南尖峰岭国家级自然保护区雨季鱼类群落结构和多样性特征,于2018年8月采用地笼、手抄网等网具对该区域内溪流的鱼类资源进行了调查。结果表明:本次调查共采集到鱼类样本310尾,隶属于6目13科21属23种。新记录鱼类共有14种,其中9种为外来物种。鱼类香农-威纳多样性指数(H')为2. 41,物种丰富度(D)为3. 84,均匀度指数(J')为0. 77,优势度为(λ)为0. 14。与历史资料相比,群落多样性显著升高,同时外来物种入侵生态风险也在升高。该研究结果丰富了尖峰岭国家自然保护区鱼类多样性基础资料,为海南热带雨林国家公园生物多样性保护策略制定提供科学依据。     

Assessment of woody species encroachment in the grasslands of Nechisar National Park,Ethiopia

Ecological survey was executed to assess woody species encroachment into the grassland plain of Nechisar National Park (NNP). Forty‐one woody species were recorded. Dichrostachys cinerea Wight & Arn., Acacia mellifera (Vahl) Benth., Acacia nilotica (L) Willd., Acacia senegal (L.) Willd., Acacia seyal Del. and Acacia tortilis (Forssk.) Hayne were among the major encroaching woody species. The majority of the woody species were found to be highly aggregated in their pattern of distribution, while only few species showed some degree of randomness. The mean woody species density was ca. 1995 woody plants ha^?1. Mean cover of woody, grass, unpalatable forbs and total herbaceous species were 31%, 58%, 68% and 121%, respectively. The woody species density and cover, unpalatable forbs and bare land cover were significantly higher in the highly grazed and fire‐suppressed part of the grassland plain. Pearson correlation coefficient matrix indicated that woody species cover and density were negatively correlated with total herbaceous and grass cover. The high woody, unpalatable forbs and bare land cover indicated the progressively increasing perennial grass species diversity deterioration in the grass plain of the Park. Decline in the grassland condition, unless reversed, will jeopardize the biological diversity as well as the aesthetic value of the NNP.     

内蒙古赛罕乌拉自然保护区冬季鸟类多样性调查

采用固定样线法于2006～2009年对内蒙古赛罕乌拉国家级自然保护区冬季鸟类组成进行了调查.共记录鸟类6目18科51种,其中有37种留鸟,9种冬候鸟,5种旅鸟,鸟类的居留型发生变化.所记录鸟类中有国家Ⅰ级重点保护鸟类1种,Ⅱ级保护鸟类13种,国家保护的有益的或者有重要经济及科学研究价值的鸟类29种.群落多样性指数值最高...     

Seasonal impact of waterfowl on communities of macrophytes in a shallow lake

From 2005 to 2007, we established bird-proof enclosures in a small, shallow and semi-permanent lake, lacking fish, at Brown Moss, Shropshire, UK, to investigate the effects of aquatic birds on seasonal growth of submerged and emergent macrophytes. The highest density of birds on the lake was in winter (110 individuals ha⁻¹) and the lowest in summer 2005 (6 ha⁻¹). Plant growth varied with season but there were significantly different (F = 8.03, p < 0.05, df = 1) standing crops of macrophytes between bird-proof enclosures (proportion of volume occupied, 0.47 ± 0.04) and control treatments (0.36 ± 0.11). Different densities of birds occurred in different areas and this was reflected in their effects. Ducks, mainly mallard (Anas platyrhynchos, Linnaeus), and teal (Anas crecca, Linnaeus), damaged plants by direct consumption, uprooting and trampling, whereas larger birds, such as mute swan (Cygnus olor, Gmelin), were able to remove Typha latifolia (Linnaeus). In summer, grazing pressure was reduced as the population of birds declined. Waterfowl caused seasonal impacts on the re-development of the water plant community. However, waterfowl herbivory had low potential to shift a macrophyte-dominated state into a phytoplankton-dominated state because aquatic plants could recover, during the growing season, when bird populations declined.     

Evolutionary analysis of three gibberellin oxidase genes in rice, Arabidopsis, and soybean

GAs are plant hormones that play fundamental roles in plant growth and development. GA2ox, GA3ox, and GA20ox are three key enzymes in GA biosynthesis. These enzymes belong to the 2OG-Fe (II) oxygenase superfamily and are independently encoded by different gene families. To date, genome-wide comparative analyses of GA oxidases in plant species have not been thoroughly carried out. In the present work, 61 GA oxidase family genes from rice (Oryza sativa), Arabidopsis, and soybean (Glycine max) were identified and a full study of these genes including phylogenetic tree construction, gene structure, gene family expansion and analysis of functional motifs was performed. Based on phylogeny, most of the GA oxidases were divided into four subgroups that reflected functional classifications. Intron/intron average length of GA oxidase genes in rice analysis revealed that GA oxidase genes in rice experienced substantial evolutionary divergence. Segmental duplication events were mainly found in soybean genome. However, in rice and Arabidopsis, no single expansion pattern exhibited dominance, indicating that GA oxidase genes from these species might have been subjected to a more complex evolutionary mechanism. In addition, special functional motifs were discovered in GA20ox, GA3ox, and GA2ox, which suggested that different functional motifs are associated with differences in protein function. Taken together our results suggest that GA oxidase family genes have undergone divergent evolutionary routes, especially at the monocot-dicot split, with dynamic evolution occurring in Arabidopsis thaliana and soybean.     

Adult human CD133/1 kidney cells isolated from papilla integrate into developing kidney tubules

Approximately 60,000 patients in the United States are waiting for a kidney transplant due to genetic, immunologic and environmentally caused kidney failure. Adult human renal stem cells could offer opportunities for autologous transplant and repair of damaged organs. Current data suggest that there are multiple progenitor types in the kidney with distinct localizations. In the present study, we characterize cells derived from human kidney papilla and show their capacity for tubulogenesis. In situ, nestin⁺ and CD133/1⁺ cells were found extensively intercalated between tubular epithelia in the loops of Henle of renal papilla, but not of the cortex. Populations of primary cells from the renal cortex and renal papilla were isolated by enzymatic digestion from human kidneys unsuited for transplant and immuno-enriched for CD133/1⁺ cells. Isolated CD133/1⁺ papillary cells were positive for nestin, as well as several human embryonic stem cell markers (SSEA4, Nanog, SOX2, and OCT4/POU5F1) and could be triggered to adopt tubular epithelial and neuronal-like phenotypes. Isolated papillary cells exhibited morphologic plasticity upon modulation of culture conditions and inhibition of asymmetric cell division. Labeled papillary cells readily associated with cortical tubular epithelia in co-culture and 3-dimensional collagen gel cultures. Heterologous organ culture demonstrated that CD133/1⁺ progenitors from the papilla and cortex became integrated into developing kidney tubules. Tubular epithelia did not participate in tubulogenesis. Human renal papilla harbor cells with the hallmarks of adult kidney stem/progenitor cells that can be amplified and phenotypically modulated in culture while retaining the capacity to form new kidney tubules. This article is part of a Special Issue entitled: Polycystic Kidney Disease.     

Structure of the BamC two-domain protein obtained by Rosetta with a limited NMR data set

The CS-RDC-NOE Rosetta program was used to generate the solution structure of a 27-kDa fragment of the Escherichia coli BamC protein from a limited set of NMR data. The BamC protein is a component of the essential five-protein β-barrel assembly machine in E. coli. The first 100 residues in BamC were disordered in solution. The Rosetta calculations showed that BamC_101-344 forms two well-defined domains connected by an ∼ 18-residue linker, where the relative orientation of the domains was not defined. Both domains adopt a helix-grip fold previously observed in the Bet v 1 superfamily. ¹⁵N relaxation data indicated a high degree of conformational flexibility for the linker connecting the N-terminal domain and the C-terminal domain in BamC. The results here show that CS-RDC-NOE Rosetta is robust and has a high tolerance for misassigned nuclear Overhauser effect restraints, greatly simplifying NMR structure determinations.     

Role of φ29 connector channel loops in late-stage DNA packaging

Double-stranded DNA bacteriophages and their eukaryotic virus counterparts have 12-fold head-tail connector assemblages embedded at a unique capsid vertex. This vertex is the site of assembly of the DNA packaging motor, and the connector has a central channel through which viral DNA passes during genome packaging and subsequent host infection. Crystal structures of connectors from different phages reveal either disordered residues or structured loops that project into the connector channel. Given the proximity to the translocating DNA substrate, these loops have been proposed to play a role in DNA packaging. Previous models have proposed structural motions in either the packaging ATPase or the connector channel loops as the driving force that translocates the DNA into the prohead. Here, we mutate the channel loops of the Bacillus subtilis bacteriophage φ29 connector and show that these loops have no active role in translocation of DNA. Instead, they appear to have an essential function near the end of packaging, acting to retain the packaged DNA in the head in preparation for motor detachment and subsequent tail assembly and virion completion.