Mechanism of adhesion and detachment at the anterior end of Merizocotyle icopae (Monogenea : Monocotylidae) including ultrastructure of the anterior adhesive matrix

The anterior adhesive mechanism was studied for Merizocotyle icopae (Monogenea: Monocotylidae). Adult anterior apertures can open and close. In addition, duct endings terminating within the apertures are everted or retracted depending on the stage of attachment. Adhesive in adults is synthesized from all 3 secretory types (rod-shaped, small and large spheroidal bodies) found within anterior apertures. All exit together and undergo mixing to produce the adhesive matrix, a process that depletes duct contents. A greater number of ducts carrying rod-shaped bodies is depleted than ducts containing spheroidal bodies which changes the ratio of secretory types present on detachment. Detachment involves elongation of duct endings and secretion of additional matrix as the worm pulls away from the substrate. The change in secretory type ratio putatively modifies the properties of the secreted matrix enabling detachment. Only after detachment do ducts refill. During attachment, individual secretory bodies undergo morphological changes. The larval and adult adhesive matrix differs. Anterior adhesive in oncomiracidia does not show fibres with banding whereas banded fibres comprise a large part of adult adhesive. The data Suggest that this is the result of adult spheroidal secretions modifying the way in which the adult adhesive matrix forms.

How to protect plants. A guide to the control of pests and diseases of plants in Hawaii.

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Diverse members of the Ralstonia solanacearum species complex cause bacterial wilts of banana

The bacterial wilts of banana known as Moko disease, Bugtok disease and blood disease are caused by members of the R. solanacearum species complex. R. solanacearum is a heterogeneous species which has been divided into 4 genetic groups known as phylotypes. Within the R. solanacearum species complex, strains that cause Moko and Bugtok diseases belong to phylotype II. The blood disease bacterium, the cause of blood disease, belongs to phylotype IV. This study employs phylogenetic analysis of partial endoglucanase gene sequences to further assess the evolutionary relationships between strains of R. solanacearum causing Moko disease and Bugtok disease and the relationship of the blood disease bacterium to other R. solanacearum strains within phylotype IV of the R. solanacearum species complex. These analyses showed that R. solanacearum Moko disease-causing strains are polyphyletic, forming four related, but distinct, clusters of strains. One of these clusters is a previously unrecognised group of R. solanacearum Moko disease-causing strains. It was also found that R. solanacearum strains that cause Bugtok disease are indistinguishable from strains causing Moko disease in the Philippines. Phylogenetic analysis of partial endoglucanase gene sequences of the strains of the blood disease confirms a close relationship of these strains to R. solanacearum strains within phylotype IV of the R. solanacearum species complex.