The Effects of Temperature on Pratylenchus scribneri and P. alleni Populations on Soybeans and Tomatoes

In soil temperature tests, rates of Pratylenchus scribneri and P. alleni reproduction were measured at various lemperatures on ''Clark 63'' and ''Cutler 71'' soybeans and ''Rutgers'' tomatoes. Recovered P. scribneri equaled or exceeded initial inoculum levels at temperatures of 27.5 C or higher on soybeans, and at 20 C or higher on tomatoes. Population increases were greatest at 3.5 C on both hosts. Populations increased on soybeans, but not on tomatoes, when soil temperature was raised from 25 to 35 C for either 3 or 9 days. Recovered P. alleni were less than the initial inoculum at 27.5 C but higher at 32 and 37.5 C and at 27.5 C on tomatoes, the lowest temperature tested for this nematode. In the field, soil temperatures 10 cm deep in eastern Kansas soybean growing areas reach 27.5 C only occasionally and for relatively short periods, which probably explains the relatively low and variable populations of P. scribneri and P. alleni on soybeans there.     

Host-parasite relations and seasonal occurrence of Paragordius tricuspidatus and Spinochordodes tellinii (Nematomorpha) in Southern France

Paragordius tricuspidatus (Dufour, 1828) and Spinochordodes tellinii (Camerano, 1888) are two sympatric species of horsehair worms in southern France. Paragordius tricuspidatus was found in only one host species, Nemobius sylvestris (Bosc, 1792), while Spinochordodes tellinii was found in nine different hosts belonging to Orthoptera Caelifera. Size of nematomorphs varied strongly, but is additionally influenced by host size (in Spinochordodes tellinii) or number of parasites per host (in Paragordius tricuspidatus). Both species have a clear seasonality with Paragordius tricuspidatus occurring from June to early August and Spinochordodes tellinii occurring in August and September.     

Development, ultrastructure, natural occurrence, and molecular characterization of Liebermania patagonica n. g., n. sp., a microsporidian parasite ot the grasshopper Tristira magellanica (Orthoptera: Tristiridae)

A new microsporidium, Liebermannia patagonica n. gen., n. sp., is described from midgut and gastric caecum epithelial cells of Tristira magellanica, an apterous grasshopper species of southern Patagonia, Argentina. L.patagonica is diplokaryotic, apansporoblastic, homosporous, and polysporoblastic. Transitional (from merogony to sporogony) stages and sporonts of L. patagonica were surrounded by host rough endoplasmic reticulum. The ovocylindrical spores measured 2.9 +/- 0.09 x 1.2 +/- 0.04 microm (fresh, n = 50), and they had an isofilar polar filament of only three coils and a cluster of tubules instead of a classical posterior vacuole. Prevalence was high (up to 80.6%) at the type locality for the four years sampled . Maximum likelihood , neighbor joining, maximum parismony analyses of the small submit rDNA all placed L.patagonica(Accession No. DQ 239917) in one with Orthosomella operophterae.     

斑点热群新疆立克次体对宿主细胞感染过程的形态学研究

对新疆立克次体(精河株,下同)感染体外培养的人胚肾传代细胞(简写MERN)和体内鸡胚卵黄囊膜细胞的标本进行了电镜观察。发现立克次体以宿主细胞膜内翻形式进入宿主细胞,在胞浆和胞核内寄生,以二分裂方式增殖;并能察见多个立克次体的链状结构;胞浆内的菌体以核膜内翻方式进入核内,以密集成丛或散在方式生长;在感染后第5—8天的MERN中,立克次体以出芽方式释放,在第8天后通过宿主细胞解体方式释放。文中讨论了新疆立克次体感染宿主细胞过程中的有关机制。我们还发现在宿主细胞内立克次体的附近有直径为20—23nm的微管结构,其功能待深入研究。     

小麦雪霉叶枯病菌侵染过程的细胞学研究

采用电镜技术研究了小麦雪霉叶枯病菌(Gerlachia nivalis)侵染过程的细胞学特征。电镜观察发现,分生孢子萌发产生的芽管由孢子细胞壁内层延伸而成;病菌侵入寄主体内后,胞间菌丝先在寄主细胞间扩展,随后胞间菌丝侵入坏死的寄主细胞,形成胞内菌丝;胞间菌丝和胞内菌丝在形态结构上无明显差异。在病菌扩展过程中,寄主细胞发生了一系列的病理变化,并最终坏死消解,寄主细胞的变化可能与病菌分泌的毒素有关。     

An electron microscopic study of the human infundibulum

Summary For a limited period during the oogenesis of Protopterus, blebs of the perinuclear cistern contain, in addition to other inclusions, a special kind of microtubular elements. Most of these blebs face parts of multiple nucleolar bodies that extend toward and make contact with the inner nuclear membrane. The microtubular lumen contains a finely dispersed material of moderate electron density which seems to be in contact with this nucleolar material.Aside from these intracisternal structures there are, within both the perinuclear cytoplasm and the nucleoplasm, similar microtubular arrays without apparent connection with the nuclear envelope. These are either enclosed by membranes derived from those of the envelope or unconfined, having escaped through breaks in their respective bounding membranes. Extracisternal tubules are presumed to have passed their period of putative functional activity and to be undergoing a process of regression and subsequent disintegration.Among possible roles attributable to the intracisternal microtubular apparatus are the following: (1) It may serve for the transport of special nucleolar components to the cytoplasm, possibly to be incorporated in the matrix of developing perinuclear mitochondria; (2) it may provide openings in the nuclear membranes for the direct passage of particulate elements between nucleus and cytoplasm; (3) it may be instrumental in the breakdown of parts of the nuclear envelope prior to its restitution during the subsequent phase of oogenesis.Supported by grants NB-00840 and NB-05219 from the U.S.P.H.S.     

Heterotrophic gain of carbon from hosts by the xylem-tapping root hemiparasite Olax phyllanthi (Olacaceae)

Heterotrophic gains of carbon from various host species by the root hemiparasitic shrub Olax phyllanthi (Labill) R.Br. were assessed using techniques based on carbon isotope discrimination (¹³C) on C3 and C4 hosts and C:N ratios of xylem sap and dry matter of host and parasite. Heterotrophic benefits (H) to Olax based on ¹³C values were 30% and 19% from two nonnative C4 hosts (Portulaca oleracea and Amaranthus caudatus respectively) compared with 13% and 15% from these hosts when computed on the basis of C:N ratios of host xylem sap and C and N increments of Olax dry matter. Nitrate was the source of N available to pot cultures of the above species and estimates based on C:N ratios assumed that all N accumulated by Olax had come from nitrate absorbed by the host. Equivalent estimates of H for Olax, grown in nitrogen-free pot culture with the native N₂-fixing host Acacia littorea as its sole source of N, indicated 63% and 51% dependence on host carbon when assessed in terms of xylem sap composition of host parasite respectively. Comparisons of xylem sap solutes of Olax and a range of partner hosts indicated marked selectivity in haustorial uptake and transfer of nitrate, amino compounds, organic acids and sugars. Possible implications of variations between hosts in absolute levels of C and inorganic and organic forms of N in xylem are discussed in relation to evidence of much better growth performance of Olax on Acacia littorea and other N₂-fixing legumes than on non-fixers.     

Social relationships of immigrant and resident female mountain gorillas. I. Male-female relationships

Adult males are important social partners for all females in mountain gorilla social groups, but male-female relationships can vary in association with variation in female residence status, male age and mating status, and relatedness. Such variation occurred in a large group observed over a 3-year period. All females associated and interacted affiliatively relatively often with a young silverback with whom all mated. Long-term resident females also did so with an old, non-breeding male to whom most were related, but recent immigrants spent little time near him and had few non-aggressive interactions with him. The old male made agonistic interventions to support relatives; interventions in female conflicts by the younger male tended to ameliorate competitive differentials that immigrants faced and may have helped him to retain them as mates. Males aggression toward females was common, most probably served as a mating tactic, and did not involve resource competition. Extensive grooming by an adolescent male suggests that males may also use affiliative behavior to develop mating relationships. Females may have competed for proximity with and social access to the younger silverback; competitive success could influence how well females and their offspring are protected by silver-backs, but the extent of such competition was not clear. Large group size may have heightened differentiation of male-female relationships and competition among females, but comparative data from smaller groups generally corroborate the findings from the large group. © 1992 Wiley-Liss, Inc.     

Allometric relationships ofmalva parviflora growing in two different bioclimatic regions

A total of 660 individual plants ofMalva parviflora, a medicinal plant in many countries, growing in two bioclimatic regions were randomly collected with the aim of examining the differences in the allometry of this herbaceous plant growing in two bioclimatic regions. Allometric relationships were found in plant height, stem width, leaf area, leaf length, leaf width, petiole length, and leaf dry weight whereas no relationship was found between plant height or petiole length with specific leaf area. Plants growing in the cool bioclimatic region showed that plant height increases more than the increase in stem width, leaf length, leaf width, and petiole length while plants growing in the warm bioclimatic region showed that plant height increase was lower than that of stem width, leaf length, leaf width, and petiole length. Plant height relationship with root length indicated that in the cool region the plant height increase was less than the increase in the root length while the opposite occurred in the warm region. These differences can be explained by the effects of the different environmental conditions present in the two bioclimatic regions such as water scarcity and availability on the growth ofM. parviflora.     

PhenUMA: a tool for integrating the biomedical relationships among genes and diseases

Background

Several types of genetic interactions in humans can be directly or indirectly associated with the causal effects of mutations. These interactions are usually based on their co-associations to biological processes, coexistence in cellular locations, coexpression in cell lines, physical interactions and so on. In addition, pathological processes can present similar phenotypes that have mutations either in the same genomic location or in different genomic regions. Therefore, integrative resources for all of these complex interactions can help us prioritize the relationships between genes and diseases that are most deserving to be studied by researchers and physicians.

Results

PhenUMA is a web application that displays biological networks using information from biomedical and biomolecular data repositories. One of its most innovative features is to combine the benefits of semantic similarity methods with the information taken from databases of genetic diseases and biological interactions. More specifically, this tool is useful in studying novel pathological relationships between functionally related genes, merging diseases into clusters that share specific phenotypes or finding diseases related to reported phenotypes.

Conclusions

This framework builds, analyzes and visualizes networks based on both functional and phenotypic relationships. The integration of this information helps in the discovery of alternative pathological roles of genes, biological functions and diseases. PhenUMA represents an advancement toward the use of new technologies for genomics and personalized medicine.

Electronic supplementary material

The online version of this article (doi:10.1186/s12859-014-0375-1) contains supplementary material, which is available to authorized users.     

Genetic relationships among Turkish sheep

Genetic relationships among Turkish sheep breeds were analysed on the basis of 30 microsatellite markers. Phylogenetic analyses based on the estimation of genetic distances revealed the closest relationships for the Akkaraman, Morkaraman and Tuj breeds, which were clearly differentiated from the others in the dendrogram. Our pattern was completely confirmed by results from the Factorial Correspondence Analysis. All the results described analysing either population parameters or individuals revealed a clear separation between the fat-tailed group and the others. These results, based on nuclear DNA, are discussed along with those already reported for these breeds through the investigation of mitochondrial DNA, which had revealed the invaluable significance of the genetic background of these Turkish sheep.     

Genetic relationships among Spanish sheep using microsatellites

Five indigenous Spanish breeds of sheep, Churra, Latxa, Manchega, Rasa–Aragonesa and Merino, with Awassi sheep as a reference breed were genotyped for 19 DNA microsatellites. Allele frequencies and mean heterozygosities revealed the greatest genetic variation in Merino sheep and the lowest in Awassis. Differences in variability were not great in the other breeds studied. The dendrograms obtained based on genetic distances showed a large differentiation between Awassi sheep and the Spanish breeds, as was to be expected from their distinct genetic origin. Merinos appeared separated from the other four breeds, of which, according to a classification based on the fleece characteristics, Churra and Latxa belong to the churro type and Manchega and Rasa–Aragonesa to the so called entrefino type, though no clear separation was evident between the two types. These results suggest that morphological data alone are insufficient for determining relationships between breeds and that studies involving genetic markers may be of great assistance.     

Interelement relationships in leaves of tropical montane trees

Chemical concentrations in leaves are reported for 14 elements in 6 tree species of a montane rain forest in Sri Lanka. The plant taxa varied greatly in chemistry and a few taxa appeared to concentrate several elements in high amounts. The chemical variability among taxonomic units was examined by comparing element-by-element concentration ratios in leaves. Several species seemed to have typical patterns of concentration ratios for certain elements and the interelement relationships of different species seemed to be repeated across varying habitat conditions.     

Forced proximity promotes the formation of enduring cooperative relationships in vampire bats

Spatial assortment can be both a cause and a consequence of cooperation. Proximity promotes cooperation when individuals preferentially help nearby partners, and conversely, cooperation drives proximity when individuals move towards more cooperative partners. However, these two causal directions are difficult to distinguish with observational data. Here, we experimentally test if forcing randomly selected pairs of equally familiar female common vampire bats (Desmodus rotundus) into close spatial proximity promotes the formation of enduring cooperative relationships. Over 114 days, we sampled 682 h of interactions among 21 females captured from three distant sites to track daily allogrooming rates over time. We compared these rates before, during and after a one-week period, during which we caged random triads of previously unfamiliar and unrelated vampire bats in proximity. After the week of proximity when all bats could again freely associate, the allogrooming rates of pairs forced into proximity increased more than those of the 126 control pairs. This work is the first to experimentally demonstrate the causal effect of repeated interactions on cooperative investments in vampire bats. Future work should determine the relative importance of mere association versus interactions (e.g. reciprocal allogrooming) in shaping social preferences.     

Chlorophyll-nutrient relationships in North Island lakes (New Zealand)

A model for the prediction of chlorophyll a in the near surface waters (1 m) of North Island lakes was developed using data from the literature and our own study of 12 North Island lakes. Annual geometric mean concentrations of chlorophyll a, total nitrogen and total phosphorus were used since no distinct growing season was discernable. Annual mean ratios of total nitrogen to total phosphorus in the near surface waters ranged between 10 and 59 (by weight). Strong correlations were obtained between log-transformed values of chlorophyll a and total nitrogen (r² = 0.53, n = 16), chlorophyll a and total phosphorus (r² = 0.71, n = 21), and between total nitrogen and total phosphorus (r² = 0.69, n = 16). However, after correcting for the high interdependency between total nitrogen and total phosphorus, only total phosphorus was found to be important in predicting chlorophyll concentrations. Much of the variance in the chlorophyll-phosphorus relation was attributable to differences in mean lake depth. Lakes with mean depths less than 11 m had significantly more chlorophyll a per unit of total phosphorus ( = 0.54 µg · µg^–1, SE = 0.05, n = 6) than lakes of greater mean depth ( = 0.17 µg · µg^–1, SE = 0.02, n = 14). When the effect of mean depth was taken into account, 89% of the variance in chlorophyll a was explained compared with 71% for the simple linear regression on total phosphorus alone.     

Structure/function relationships in methylotrophic yeasts

Abstract This symposium marks the 15th anniversary of the discovery of microbodies in methylotrophic yeasts. In the intervening years much has been learned about the structure, function and biogenesis of these organelles and these advances are described. As our endeavours continued, unexpected results have confused commonly held views. This was for instance the case when microbody-minus mutants of yeasts became available which showed that some microbody matrix enzymes may be functional when present in the cytosol while others are not. At the molecular level, our understanding of structure/function relationships is also expanding. Examples are structural elements which relate to protein topogenesis and function of enzymes in different cell compartments. Other, perhaps more unusual, adaptations have also been encountered; some involve protein-protein interactions or even modified cofactors which possibly have helped methylotrophic yeasts to establish and/or maintain themselves in natural ecosystems.     

Genic differentiation and phylogenetic relationships within two New World bat genera

Phylogenetic placement of taxa within the two New World leaf-nosed bat genera, Tonatia and Micronycteris was carried out using allozymic characters. Of particular interest were the relationships between the karyotypically megaevolved species and their proposed congeners. Neither of the two karyotypically megaevolved Tonatia species shared synapomorphic allozymes with the other Tonatia taxa. In contrast, the three Micronycteris species identified as having undergone this unusual mode of karyotypic evolution fall within a common evolutionary assemblage with all but one of their congeners. Measures of genic similarity among the Tonatia and Micronycteris species yield relatively low Nei identity values. No correlation is found when the number of karyotypic and allozymic changes since a common ancestor are compared.     

Direct cytoplasm-cytoplasm connection: an unusual host-parasite interaction of the tremelloid mycoparasiteTetragoniomyces uliginosus

Summary The cellular interaction ofTetragoniomyces uliginosus andRhizoctonia sp. was restudied by transmission electron microscopy. During the first stages of interaction a body of medium electron density is visible at the center of the haustorial apex in close association with the plasmalemma. A single micropore is produced between the haustorial filament and the host cell. Cytoplasmic connection via the pore always occurred. The pore membrane is continuous with the plasmalemma of both cells. The protoplasts of both the haustorium and the host cell fuse via the micropore. An electron transparent to dense body occlude the pore. Among basidiomycetes, direct connection between the parasite and host protoplasts represents a hitherto unknown type of parasitic interaction.Part 65 of the series Studies in Heterobasidiomycetes.