Ultrastruktur Morfologi Polen Arundina graminifolia (D.Don) Hochr. (Orchidaceae)

Pollen morphology of three variants of Arundina graminifolia in West Sumatra was examined. The pollen types, shapes, apertures and ornamentations were examined using scanning electron microscope. There was variation of pollen shape between three variant of Arundina graminifolia. There was different of pollen shape white variant to pink and purple variant. The pollen shape of white variant were oblate sferoidal. The prolate shapes were detected at pink and purpe variant. Three variants Arundina graminifolia have the same ornamentation exine that is the reticulum and there kolpus of the same type, namely tri-kolpate and tetra-kolpate

The bivalve mollusc Mactra corallina: genetic evidence of existing sibling species

The rayed trough-shell Mactra corallina Linnaeus 1758 is a surf clam that inhabits the Atlantic Ocean, Black Sea and Mediterranean Sea and represents a commercially important bivalve. This species is present with two different and well-defined sympatric morphotypes, which differ mainly for the colour of the shell (white in the corallina morph, and brown-banded in the lignaria morph). The aim of this work is to resolve the confused and contradictory systematics of the bivalves belonging to M. corallina putative species by analysing molecular and morphological features. Fifteen specimens of M. corallina corallina (white variant) and 19 specimens of M. corallina lignaria (brown variant) were collected in the North Adriatic Sea and analysed by four molecular markers (12S, 16S, 18S and COI genes, partial sequences). Genetic analyses clearly support the presence of two different species, which were previously ascribed to M. corallina. In addition, 35 specimens identified on a morphological basis as M. c. corallina and 28 specimens identified as M. c. lignaria collected in the same area were used for a morphometric analysis. A positive correlation was found between the maximum width of shell (W), antero-posterior length and between W and the height of specimens from umbo to ventral margin, thus adding to molecular data.

Variations in the csgD Promoter of Escherichia coli O157:H7 Associated with Increased Virulence in Mice and Increased Invasion of HEp-2 Cells

ABSTRACT Promoter alterations in the csgD gene of Escherichia coli O157:H7 strains ATCC 43894 and ATCC 43895 are associated with variations in curli expression and the ability to bind Congo red dye. Red variants of each strain were more invasive for cultured HEp-2 cells than were white variants. An ATCC 43895 red variant was more virulent than a white variant in a mouse model. However, there were no differences in Shiga toxin production between red and white variants.