Cytology of parthenogenesis of five Meloidogyne species

La présente étude a porté sur l'ovogenèse de plusieurs isolats à parthénogenèse méiotique facultative - #Meloidogyne hapla race A, #M. chitwoodi, #M. fallax - et à parthénogenèse améiotique (mitotique) - #M. hapla race B, #M. javanica et l'isolat Xa appartenant à une espèce non identifiée - et ce au moyen d'une technique de coloration fluorescente au Hoechst 33258. En l'absence de fécondation, le nombre de chromosomes somatiques est rétabli par fusion du pronucleus et du second corps polaire chez les isolats de #M. hapla race A, dans tous les autres cas la réduction chromosomique est compensée par la duplication des chromosomes dans le noyau de l'oeuf après la première division. Chez l'une des lignées mono-femelles de l'isolat Xa le développement embryonnaire, génétiquement contrôlé, se produit à l'intérieur de la femelle. Cette étude confirme la grande variabilité des modes de reproduction des espèces de #Meloidogyne ce qui peut expliquer leur succès mondial. Dans un isolat de #M. hapla race A, seuls 12% des oocytes des femelles fécondées contiennent des spermatozoïdes et ce sont les oocytes en prophase 1 - au lieu de la prométaphase 1 - qui sont observés en position postérieure à la spermathèque. (Résumé d'auteur

Multiple supernumerary chromosomes in the pseudogamous parthenogenetic flatworm Polycelis nigra:lineage markers or remnants of genetic leakage?

Polycelis nigra is a free-living simultaneous hermaphroditic flatworm that has amphimictic and pseudogamous parthenogenetic biotypes. Sexual individuals are always diploid (2n = 16) and pseudogamous parthenogens are polyploid (usually triploid). Two types of supernumerary chromosomes are found in parthenogens, those resembling autosomes ("A-like") and typical B chromosomes, both of which reach frequencies in populations of close to 100%. Experiments measuring the transmission rates of the B chromosomes indicated that they are potentially inherited via the male line, escaping expulsion by pseudogamous parthenogenesis. This study used the C-banding technique to demonstrate (i) that there is a single morphologically distinct B chromosome (B1) and (ii) that then are two "A-like" chromosomes that can be considered B chromosomes (B2 and B3) and which are not simple polysomics of one of the eight autosomes. As there is no genetic exchange between pseudogamous parthenogenetic lineages, two different individuals carrying a similar B morph must either have received it through common ancestry (a lineage marker) or have acquired it horizontally from another parthenogenetic lineage (leakage). C-banding further revealed intra-individual heteromorphy for band regions on chromosomes 5 and 8. This supports the karyotypic observation that oogenesis is preceded by premeiotic chromosome doubling followed by pairing of replicate homologues

Chromosome number of the potato cyst nematode Globodera rostochiensis

Le nombre de chromosome de #Globodera rostochiensis$ a été déterminé par l'analyse de leurs configurations bivalentes au stade métaphase I, de cellules au stade de réduction méiotique pendant l'oogenèse, et de cellules en mitose somatique au cours de divisions embryonnaires prématurées. Le nombre de chromosomes diploïde est 2 n = 18. L'utilisation du fluorochrome Hoechst 33528 a facilité la détermination du nombre de chromosomes dans les globules polaires. Les premières divisions ont été observées en utilisant une méthode d'écrasement améliorée. (Résumé d'auteur

Theory of mind in utterance interpretation: the case from clinical pragmatics

The cognitive basis of utterance interpretation is an area that continues to provoke intense theoretical debate among pragmatists. That utterance interpretation involves some type of mind-reading or theory of mind (ToM) is indisputable. However, theorists are divided on the exact nature of this ToM-based mechanism. In this paper, it is argued that the only type of ToM-based mechanism that can adequately represent the cognitive basis of utterance interpretation is one which reflects the rational, intentional, holistic character of interpretation. Such a ToM-based mechanism is supported on conceptual and empirical grounds. Empirical support for this view derives from the study of children and adults with pragmatic disorders. Specifically, three types of clinical case are considered. In the first case, evidence is advanced which indicates that individuals with pragmatic disorders exhibit deficits in reasoning and the use of inferences. These deficits compromise the ability of children and adults with pragmatic disorders to comply with the rational dimension of utterance interpretation

Updated cost-effectiveness and risk-benefit analysis of two infant rotavirus vaccination strategies in a high-income, low-endemic setting.

Since 2013, a biennial rotavirus pattern has emerged in the Netherlands with alternating high and low endemic years and a nearly 50% reduction in rotavirus hospitalization rates overall, while infant rotavirus vaccination has remained below 1% throughout. As the rotavirus vaccination cost-effectiveness and risk-benefit ratio in high-income settings is highly influenced by the total rotavirus disease burden, we re-evaluated two infant vaccination strategies, taking into account this recent change in rotavirus epidemiology

Do Two Symmetry Breaking Transitions in Photosynthetic Light Harvesting Complexes Form One, Two or More Kibble Zurek Model Topological Defects?

Kibble and Zurek proposed that rapid symmetry breaking transitions in the hot, early universe could result in causally disconnected topological defects such as cosmic strings. This type of first order transition has analogues in certain second order transitions present in condensed matter such as liquid crystals, super fluids, and charge density waves in terms of flux tubes or vortices. Recently, we discovered that Rhodopseudomonas acidophilus photosynthetic light harvesting complex might have different types of coherent ground and excited states, suggesting that there are two different symmetry breaking transitions. The B 850 ground states comprise eight identical rings each containing 18 bacteriochlorophyll components, and each ring has undergone a Bose Einstein phase transition to a charge density wave that lowers the energy. The excited state coherence results from polariton formation from the non-crossing of bosons, here an extension of exciton theory. The result is short-lived quasi-particles with very low mass that can form an unusual BEC. We suggest the oriented, circular B 850 and enclosed singlet B 875 compounds create a new cavity structure with some attributes of a nano pillar. Since both the ground and excited states should contain solitons, we envisage three fast light pulse experiments could be able to map both the Kibble Zurek Model phase transitions and energy transfers as a function of light intensity and time in this complex at room temperature