Kinetics of morphogen gradient formation

In the developing fly wing, secreted morphogens such as Decapentaplegic (Dpp) and Wingless (Wg) form gradients of concentration providing positional information. Dpp forms a longer-range gradient than Wg. To understand how the range is controlled, we measured the four key kinetic parameters governing morphogen spreading: the production rate, the effective diffusion coefficient, the degradation rate, and the immobile fraction. The four parameters had different values for Dpp versus Wg. In addition, Dynamin-dependent endocytosis was required for spreading of Dpp, but not Wg. Thus, the cellular mechanisms of Dpp and Wingless spreading are different: Dpp spreading requires endocytic, intracellular trafficking.     

Absence of geographical structure of morphological variation in <Emphasis Type="Italic">Juniperus oxycedrus</Emphasis> L. subsp. <Emphasis Type="Italic">oxycedrus</Emphasis> in the Balkan Peninsula

We examined leaf and mature seed cone variation of Juniperus oxycedrus L. subsp. oxycedrus in 12 natural populations across the species range in the Balkan Peninsula. We measured 10 morphological traits from a minimum of 100 leaves in each of 190 individuals, and two morphological traits from 30–50 seed cones in each of 94 females. High phenotypic variation was found, but no geographical structure or cline across populations was detected for any of the studied traits. Mean values of comparable leaf and cone morphological traits did not differ considerably from values reported elsewhere. Gender dimorphism in leaf morphology was detected, but it was not distributed uniformly throughout the studied area. An ANOVA model with both nested and crossed effects revealed that the largest proportion of the total variation was, as expected, contained within populations, partly as among-tree variation (18–47%, depending on the trait) and partly as within-tree variation (33–77%), which was remarkably high. Gender dimorphism explained only 0–3% of the total variation. Differences among populations (2–23%) were significant for all studied traits except one; however, PCA showed no clear geographical differentiation of the studied populations. This lack of phylogeographical structure may be the consequence of repeatedly occurring colonisation-retreat scenarios and suggests the existence of several small refugial populations scattered over a large part of the Balkan Peninsula in the Pleistocene. Further research including palaeobotanical and molecular genetic studies will be needed to better understand the forces that shaped current variation patterns of J. oxycedrus L. subsp. oxycedrus in the Balkan Peninsula.     

Serological survey of Q fever in Crete, southern Greece

Coxiella burnetii, the causative agent of Q fever, is an obligatory intracellular bacterium with worldwide distribution. The aim of this study was to determine the prevalence of C. burnetii phase II antibodies in two different groups (high and low risk) of healthy human population and investigate the epidemiological characteristics of the infection in the island of Crete (southern Greece). Collection and testing by IFA of 493 sample sera for IgG and IgM antibodies against C. bumetii phase II antigen indicated a prevalence of IgG antibodies of 48.7%. Of the seropositive individuals, 34% also revealed IgM seropositive antibody titers. Analysis of 225 sample sera by IFA from high risk population presented a prevalence for C. burnetii of 62.2%. Our findings revealed that C. burnetii is highly endemic in Crete, indicating a high exposure of the population to the pathogen regardless of occupation or place of residence.     

Buried in the sand: Uncovering the ecological roles and importance of rays

Rays (superorder Batoidea) are the most diverse group of elasmobranchs, and many are threatened with extinction. However, there remain areas where research on the ecology of this group is lacking, from trophic interactions to their importance to ecosystem structure and function. Such ecological insights are critical for predicting the potential consequences of changes in their population sizes. Our aim was to synthesize the existing ray ecology literature and identify key knowledge gaps in order to provide a framework for future research. Numerous studies describe ray diets, and the number of studies using biochemical methods to address ray trophic interactions is increasing. The implications of ray predator–prey interactions on population dynamics of prey and how ray foraging might influence ecosystem dynamics through bioturbation remain relatively unexplored, despite claims that rays are ecologically important because they are bioturbators and because of their potential to deplete stocks of commercially important bivalves. Therefore, to better integrate rays in our understanding of marine community dynamics, there is a need to: (i) combine behavioural data with dietary information to describe predator–prey interactions; (ii) understand how ray bioturbation affects biogeochemical cycles and infaunal communities; (iii) elucidate conditions under which rays might initiate or transmit trophic cascades through consumptive and non‐consumptive pathways; and (iv) consider anthropogenic influences on the ecological roles and importance of rays.     

Phylogentic analysis of Anaplasma ovis strains isolated from sheep and goats using groEL and mps4 genes

Evidence of Anaplasma spp. in goats and sheep in Cyprus has been demonstrated by previous research. Herein, further research was performed for the identification of the exact Anaplasma spp. resulting in the identification of Anaplasma ovis strains in all samples examined. We used a bioinformatics as well as a molecular approach (study of groEl and mps4 genes) in order to verify the validity of the results. All samples depicted the presence of A. ovis regardless of the host (goat or sheep).     

Helper component-transcomplementation in the vector transmission of plant viruse

ABSTRACT Plant viruses are most frequently transmitted from one host plant to another by vectors. In noncirculative vector transmission, the virus does not process through a cycle within the vector body. Instead, upon acquisition by the vector, viruses are retained in the mouth parts or the anterior gut; from there, they will be subsequently released in a new host plant. Two molecular strategies have been described for the virus-vector interaction. In the capsid strategy, the virus coat interacts directly with binding sites in the vector mouth parts, whereas an additional nonstructural protein, designated helper component (HC), is required in the helper strategy. The HC and virus particles can be acquired sequentially, and this property introduces the possibility that an HC acquired first by the vector assists the transmission of virus particles located in the same cell, in other cells, or even in other host plants probed by the vector. Such a phenomenon is here called HC-transcomplementation. Surprisingly, the existing definition of HC does not explicitly include the concept of HC-transcomplementation, and it is generally omitted in the literature in any consideration of the virus biology other than the molecular interaction with the vector. Here we propose an extended definition of HC and emphasize the concept of HC-transcomplementation that distinguishes the helper strategy from any other type of vector transmission and may have consequences at the level of the virus population genetics and evolution.     

Allozyme Variation Among Some Pearl Millet (<Emphasis Type="Italic">Pennisetum glaucum</Emphasis> L.) Cultivars Collected from Tunisia and West Africa

Allozyme variation was assessed in a collection of pearl millet cultivars derived from three different regions of traditional cultivation of this cereal in Tunisia and West African countries. Using starch gel electrophoresis, 11 loci corresponding to seven enzyme staining systems were identified. Important within-cultivar genetic diversity was detected. Genetic diversity within Tunisian cultivars was similar and was more pronounced than for West African ones. This result could be explained by the low level of the human selection characterizing the Tunisian cultivars. Most of the total genetic diversity is maintained within subregions suggesting little genetic differentiation. Cluster analysis did not reveal separate clusters for the various subregion cultivars. However the cluster analysis should help in the selection of interesting genotypes for future breeding programs.     

Fatty acid composition and biometry of five Greek Artemia populations suitable for aquaculture purposes

Evaluation of a new‐to‐science Artemia population and comparison with four other existing populations were carried out. Five parthenogenetic Artemia populations from the following Greek saltworks were studied: Alyki (a new population), Kalloni, Milos, Polychnitos and Messolongi. The diameters of non‐decapsulated and decapsulated cysts as well as the lengths of nauplii instar stages I, II and III were measured. In addition, the fatty acid composition of decapsulated cysts was estimated. The cyst size of the Alyki population was the smallest, with the largest chorion found in Greece so far. The Messolongi population had the largest cysts, with the smallest chorion of all five populations. The diameter of the non‐decapsulated cysts was highly related (P<0.01) to the length of the nauplii instar I, II and III. The diameter of decapsulated cysts was found to be the most stable and reliable biometric characteristic. The study of their fatty acids profiles revealed that the Polychnitos and Messolongi populations are suitable as live food for freshwater species, while the Alyki, Milos and Kalloni populations are suitable for marine species, having high levels (8.9%, 11.2% and 12.5% respectively) of eicosapentaenoic acid and detectable amounts (0.3%, 0.1% and 0.2% respectively) of docosahexaenoic acid.