Freshwater crayfish invasions in South Africa: past,present and potential future

Freshwater crayfish invasions have been studied around the world, but less so in Africa, a continent devoid of native freshwater crayfish. The present study reviews historical and current information on alien freshwater crayfish species introduced into South Africa and aims to indicate which areas are at risk from invasion. As is the case elsewhere, South Africans have shown a keen interest in both farming and keeping freshwater crayfish as pets, which has resulted in Cherax cainii, Cherax destructor, Cherax quadricarinatus and Procambarus clarkii being introduced to the country. There is evidence of successful establishment in the wild for C. quadricarinatus and P. clarkii in different parts of the country. Species distribution models suggest that the eastern part of the country and parts of the Eastern and Western Cape are at higher risk of invasion. At present, illegal translocations represent the most likely pathway of crayfish spread in South Africa. A continued risk of invasion by freshwater crayfish species in South Africa is highlighted, which reinforces the need for more research, as well as for strong mitigation measures, such as stronger policing of existing regulations, management or eradication where feasible and public education.     

电子供体及受体对棕色固氮菌抗氨阻遏能力的影响

电子供体连二亚硫酸钠,甲基紫精及电子受体亚甲蓝均能强烈的抑制棕色固氮菌表达固氮活性,并引起该菌的抗氨阻遏能力减弱,适当提高氧压,能提高菌体的固氮活性近15％,但过高的氧分压反而抑制菌体的固氮活性,此外,提高氢分压能降低棕色固氮菌菌体内的还原电位,从而达到提高菌体抗氨阻遏能力的效果。     

Isolation and characterization of microsatellites in Neogobius kessleri (Perciformes,Gobiidae) and cross‐species amplification within the family Gobiidae

Fourteen polymorphic microsatellites were isolated from Neogobius kessleri, a benthic fish of Ponto‐Caspian origin which has been recently introduced into the Middle and Upper Danube River. Number of alleles and heterozygosity per locus in a sample of 32 fish individuals ranged from two to four and from 0.13 to 0.75, respectively. These primers will be useful in determining the population structure of N. kessleri. In addition, successful cross‐amplification was obtained for four related species, N. melanostomus, N. fluviatilis, N. gymnotrachelus and Proterorhinus marmoratus. These microsatellite loci may be useful for the evaluation of the origin of non‐native goby populations.     

A mRNA landscape of bovine embryos after standard and MAPK-inhibited culture conditions: a comparative analysis

Background

Genes and signalling pathways involved in pluripotency have been studied extensively in mouse and human pre-implantation embryos and embryonic stem (ES) cells. The unsuccessful attempts to generate ES cell lines from other species including cattle suggests that other genes and pathways are involved in maintaining pluripotency in these species. To investigate which genes are involved in bovine pluripotency, expression profiles were generated from morula, blastocyst, trophectoderm and inner cell mass (ICM) samples using microarray analysis. As MAPK inhibition can increase the NANOG/GATA6 ratio in the inner cell mass, additionally blastocysts were cultured in the presence of a MAPK inhibitor and changes in gene expression in the inner cell mass were analysed.

Results

Between morula and blastocyst 3,774 genes were differentially expressed and the largest differences were found in blastocyst up-regulated genes. Gene ontology (GO) analysis shows lipid metabolic process as the term most enriched with genes expressed at higher levels in blastocysts. Genes with higher expression levels in morulae were enriched in the RNA processing GO term. Of the 497 differentially expressed genes comparing ICM and TE, the expression of NANOG, SOX2 and POU5F1 was increased in the ICM confirming their evolutionary preserved role in pluripotency. Several genes implicated to be involved in differentiation or fate determination were also expressed at higher levels in the ICM. Genes expressed at higher levels in the ICM were enriched in the RNA splicing and regulation of gene expression GO term. Although NANOG expression was elevated upon MAPK inhibition, SOX2 and POU5F1 expression showed little increase. Expression of other genes in the MAPK pathway including DUSP4 and SPRY4, or influenced by MAPK inhibition such as IFNT, was down-regulated.

Conclusion

The data obtained from the microarray studies provide further insight in gene expression during bovine embryonic development. They show an expression profile in pluripotent cells that indicates a pluripotent, epiblast-like state. The inability to culture ICM cells as stem cells in the presence of an inhibitor of MAPK activity together with the reported data indicates that MAPK inhibition alone is not sufficient to maintain a pluripotent character in bovine cells.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-015-1448-x) contains supplementary material, which is available to authorized users.     

In Vivo Chemical and Structural Analysis of Plant Cuticular Waxes Using Stimulated Raman Scattering Microscopy

The cuticle is a ubiquitous, predominantly waxy layer on the aerial parts of higher plants that fulfils a number of essential physiological roles, including regulating evapotranspiration, light reflection, and heat tolerance, control of development, and providing an essential barrier between the organism and environmental agents such as chemicals or some pathogens. The structure and composition of the cuticle are closely associated but are typically investigated separately using a combination of structural imaging and biochemical analysis of extracted waxes. Recently, techniques that combine stain-free imaging and biochemical analysis, including Fourier transform infrared spectroscopy microscopy and coherent anti-Stokes Raman spectroscopy microscopy, have been used to investigate the cuticle, but the detection sensitivity is severely limited by the background signals from plant pigments. We present a new method for label-free, in vivo structural and biochemical analysis of plant cuticles based on stimulated Raman scattering (SRS) microscopy. As a proof of principle, we used SRS microscopy to analyze the cuticles from a variety of plants at different times in development. We demonstrate that the SRS virtually eliminates the background interference compared with coherent anti-Stokes Raman spectroscopy imaging and results in label-free, chemically specific confocal images of cuticle architecture with simultaneous characterization of cuticle composition. This innovative use of the SRS spectroscopy may find applications in agrochemical research and development or in studies of wax deposition during leaf development and, as such, represents an important step in the study of higher plant cuticles.The majority of land plants possess an extracellular, waxy cuticle that covers the surface of their aerial parts and protects them against desiccation, external physical and chemical stresses, and a variety of biological agents (Grncarevic and Radler, 1967; Barthlott and Neinhuis, 1997; Krauss et al., 1997; Ristic and Jenks, 2002; Yeats and Rose, 2013). The cuticle is a composite layer composed mainly of cutin and overlaid by cuticular waxes. Cutin is a macromolecular structure consisting primarily of hexadecanoic (palmitic) and octadecenoic (vaccenic) acids that are covalently linked by ester bonds to generate a rigid, three-dimensional network that is embedded with polysaccharides. Cuticular waxes are composed of long-chain (C₂₀–C₄₀) aliphatic molecules derived from fatty acids (Samuels et al., 2008), and studies over the last several decades have identified structural and regulatory constituents of the biosynthetic pathways of cuticular components (Kolattukudy, 1981; Beisson et al., 2012). In addition to the physiochemical properties conferred by its lipid components, the architecture of the cuticle plays an essential role in physiological function. For example, through understanding the properties of the cuticular structure, the extraordinary superhydrophobicity of the Lotus spp. leaf has been mimicked in micro- and nanotechnology to generate self-cleaning surfaces (Bhushan and Jung, 2006; Bhushan et al., 2009; Koch et al., 2009).As may be expected, given the diversity of plants, the habitats they inhabit, and individual life histories, the morphology and composition of plant cuticle varies extensively between and within species and includes plate-, needle-, and pillar-shaped wax crystals (Barthlott et al., 2008). In some species, cuticular wax composition is known to vary with depth, giving rise to chemically distinguishable layers (Yeats and Rose, 2013). Finally, the cuticle is increasingly shown to be important in development (Koornneef et al., 1989; Yeats and Rose, 2013) and pathogenesis (Lee and Dean, 1994; Gilbert et al., 1996; Bessire et al., 2007; Delventhal et al., 2014). It is therefore unsurprising that interest in cuticle composition, structure, and physiology is increasing (Buschhaus et al., 2014; Hen-Avivi et al., 2014; Heredia-Guerrero et al., 2014; Xu et al., 2014). Moreover, a greater understanding of the relationship between structure and chemical composition of cuticle waxes is vital for enhancing agriculture yields, as it will further our knowledge of how plants regulate water balance and inform the application of nutrition (foliar feeds) and pesticides, leading to improved formulation strategies for agrochemicals.The chemical composition and topological architecture of cuticular waxes are both critical for optimal physiological function. Analyses of these essential properties have typically been performed separately. Cuticle wax composition is normally determined using gas chromatography; cuticle ultrastructure may be analyzed using destructive imaging techniques such as scanning electron microscopy (SEM; Baker and Holloway, 1971; Jetter et al., 2000; Barthlott et al., 2008) and laser desorption ionizing mass spectroscopy (Jun et al., 2010) or, in vivo, using nondestructive real-time techniques, including white-light scanning interferometry (Kim et al., 2011), atomic force microscopy (Koch et al., 2004), confocal microscopy in reflectance mode (Veraverbeke et al., 2001), fluorescence microscopy of chemical stains (Pighin et al., 2004), coherent anti-Stokes Raman scattering (CARS) microscopy (Yu et al., 2008; Weissflog et al., 2010), and total internal reflection Raman spectroscopy (Greene and Bain, 2005). Despite the advances in our understanding of the cuticle that have been made with these techniques, there is a great need for techniques that combine chemical and structural information to provide in situ high-resolution chemical analysis of epicuticle waxes.Techniques based on vibrational spectroscopy offer in situ chemical analysis derived from the vibrational frequencies of molecular bonds within a sample. However, due to water absorption and the intrinsically low spatial resolution associated with the long infrared (IR) wavelengths required to directly excite molecular vibrations, IR absorption techniques have limited value for bioimaging. Raman scattering, however, provides analysis of vibrational frequencies by examining the inelastic scattering of visible light. Raman scattered light is frequency shifted with respect to the incident light by discrete amounts that correspond to the vibrational frequencies of molecular bonds within the sample. The spectrum of Raman scattered light consists of a series of discrete peaks that each correspond to a molecular bond and can be regarded as a chemical fingerprint holding a wealth of information regarding chemical composition. Unfortunately, Raman scattering is an extremely weak effect, and typical signals from biological samples are at least six orders of magnitude weaker than those from fluorescent labels. This severely limits the application of Raman for studying living systems because long acquisition times (100 ms–1 s per pixel) and relatively high excitation powers (several hundred milliwatts) are required to image most biomolecules with sufficient sensitivity. Furthermore, the lack of sensitivity is compounded by autofluorescence, which in plant tissues completely overwhelms the Raman signal, prohibiting its application in planta.Far stronger Raman signals can be obtained using coherent Raman scattering (CRS; Min et al., 2011). CRS achieves a Raman signal enhancement by focusing the excitation energy onto a specific molecular vibrational frequency (Fig. 1A). A pump and Stokes beam, with frequencies ω_p and ω_S, respectively, are incident upon the sample, with their frequency difference (ω_p–ω_S) tuned to match the molecular vibrational frequency of interest. Under this resonant condition, the excitation fields efficiently drive bonds to produce a strong nonlinear coherent Raman signal. When applied in microscopy format, the nonlinear nature of the CRS process confines the signal to a submicron focus that can be scanned in space, allowing three-dimensional confocal-like mapping of biomolecules. CRS microscopy has particular advantages for bioimaging: (1) Chemically specific contrast is derived from the vibrational signature of endogenous biomolecules within the sample, negating the need for extraneous labels/stains; (2) Low-energy, near-IR excitation wavelengths can be employed, which reduces photodamage and increases depth penetration into scattering tissues; and (3) The CRS process does not leave sample molecules in an excited state, does not suffer from photobleaching, and can be used for time course studies.Open in a separate windowFigure 1.Schematic representation of the two CRS processes: CARS and SRS. A, Energy level diagrams for the CARS and SRS processes, showing the pump (green), Stokes (red), and anti-Stokes (blue) photon energies. B, Diagrammatic representation of the input and output spectra for CARS and SRS, showing the gain and loss in the pump (red) and Stokes (green) beams, respectively. ΔI_S, Change in Stokes beam intensity; ΔI_p, change in pump beam intensity. C, Diagrammatic representation of the modulation transfer detection scheme used to detect stimulated Raman gain and loss with high sensitivity.CRS microscopy may be achieved by detecting either CARS or stimulated Raman scattering (SRS).     

基于红外相机技术分析鼬獾的活动节律

鼬獾(Melogale moschata)是食肉目鼬科鼬獾属动物,在我国分布广泛、种群数量丰富,但有关鼬獾的生态研究报导比较少.为掌握鼬獾的活动节律及其影响因素,2017年2月至2019年2月,利用红外相机技术对江西省桃红岭梅花鹿国家级自然保护区、九岭山国家级自然保护区和齐云山国家级自然保护区的鼬獾进行了监测,每个保护...     

An unexpected increase in pituitary sensitivity to gonadotrophin releasing hormone after treatment with porcine follicular fluid (inhibin) in immature hemicastrate rats

Porcine follicular fluid (PFF) contains a factor (inhibin or folliculostatin) which is reported to selectively inhibit the secretion of follicle-stimulating hormone (FSH) from the anterior pituitary gland. Chronic treatment of hemicastrate immature rats with PFF is able to partially inhibit the FSH-mediated hypertrophy of the remaining testis. However, the pituitaries from PFF-treated rats are paradoxically very sensitive to stimulation with gonadotrophin-releasing hormone (GnRH) and secrete significantly more FSH than control glands. Furthermore, this increased sensitivity results in a large increase in luteinizing hormone (LH) secretion. These observations suggest that under certain circumstances PFF is not selective for FSH and that it surprisingly stimulates rather than inhibits gonadotrophin secretion.     

Analysis of Amblyomma sculptum haplotypes in an area endemic for Brazilian spotted fever

Amblyomma sculptum (Ixodida: Ixodidae) Berlese, 1888, a member of the Amblyomma cajennense complex, is the major vector of Brazilian spotted fever (BSF) in southeastern Brazil. In this study, the genetic diversity of A. sculptum populations in the state of Rio de Janeiro (RJ), Brazil, was investigated because genetic variability in tick populations may be related to vector competence. Samples of A. sculptum from 19 municipalities in 7 regions of RJ were subjected to DNA extraction, amplification and sequencing of D‐loop, cytochrome oxidase II and 12S rDNA mitochondrial genes. These sequences were used to map the genetic diversity of this tick. Amblyomma sculptum populations are genetically diverse in RJ, especially in the South Centre and Highland regions. Few unique haplotypes were observed in all populations, and the majority of genetic variation found was among ticks within each population. Phylogenetic reconstruction reinforced the assumption that all the haplotypes identified in RJ belong to A. sculptum. However, some RJ haplotypes are closer to A. sculptum from Argentina than to A. sculptum from elsewhere in Brazil. In RJ, A. sculptum has high genetic diversity, although little genetic differentiation. Observations also indicated a high level of gene flow among the studied populations and no evidence of population structure according to region in RJ.     

Feather ornaments are dynamic traits in the Great Tit Parus major

In behavioural studies it has been common to quantify plumage colours or ornaments over a range of dates and link them to fitness characteristics without accounting for seasonal changes in these traits. Such changes are likely to be widespread among birds, yet we lack assessments of this variability within individuals. We studied both within‐ and between‐individual temporal changes in Great Tit Parus major ornaments, specifically the melanin‐based black breast stripe and the pigment‐free white cheek patch. During the non‐breeding season both ornaments varied. In juveniles and adult females, the area of the breast stripe first rose and then, from near the end of December, decreased. In adult males there was a linear decrease. In the cheek patch, the irregularity of the cheek borders showed either a linear (adults) or a non‐linear (juveniles) increase as the season progressed. In individuals repeatedly sampled during the same winter, the decrease in the size of the breast stripe was larger for males than females and there was an overall decrease in the regularity of the cheek borders. There was no relationship between the size of the breast stripe and the white cheek patch irregularities or the cheek patch area. These results imply that more attention should be paid to quantification, within individuals, of the components of expression of phenotypic traits. In addition, we suggest that further research should focus on explaining the causes and functions of ornament change.     

Use of vector control to protect people from sleeping sickness in the focus of Bonon (Côte d’Ivoire)

BackgroundGambian human African trypanosomiasis (gHAT) is a neglected tropical disease caused by Trypanosoma brucei gambiense transmitted by tsetse flies (Glossina). In Côte d’Ivoire, Bonon is the most important focus of gHAT, with 325 cases diagnosed from 2000 to 2015 and efforts against gHAT have relied largely on mass screening and treatment of human cases. We assessed whether the addition of tsetse control by deploying Tiny Targets offers benefit to sole reliance on the screen-and-treat strategy.Methodology and principal findingsIn 2015, we performed a census of the human population of the Bonon focus, followed by an exhaustive entomological survey at 278 sites. After a public sensitization campaign, ~2000 Tiny Targets were deployed across an area of 130 km² in February of 2016, deployment was repeated annually in the same month of 2017 and 2018. The intervention’s impact on tsetse was evaluated using a network of 30 traps which were operated for 48 hours at three-month intervals from March 2016 to December 2018. A second comprehensive entomological survey was performed in December 2018 with traps deployed at 274 of the sites used in 2015. Sub-samples of tsetse were dissected and examined microscopically for presence of trypanosomes. The census recorded 26,697 inhabitants residing in 331 settlements. Prior to the deployment of targets, the mean catch of tsetse from the 30 monitoring traps was 12.75 tsetse/trap (5.047–32.203, 95%CI), i.e. 6.4 tsetse/trap/day. Following the deployment of Tiny Targets, mean catches ranged between 0.06 (0.016–0.260, 95%CI) and 0.55 (0.166–1.794, 95%CI) tsetse/trap, i.e. 0.03–0.28 tsetse/trap/day. During the final extensive survey performed in December 2018, 52 tsetse were caught compared to 1,909 in 2015, with 11.6% (5/43) and 23.1% (101/437) infected with Trypanosoma respectively.ConclusionsThe annual deployment of Tiny Targets in the gHAT focus of Bonon reduced the density of Glossina palpalis palpalis by >95%. Tiny Targets offer a powerful addition to current strategies towards eliminating gHAT from Côte d’Ivoire.