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Full-Text Articles in Life Sciences
Fine-Structure Of Minchinia Sp (Haplosporida) Sporulation In Mud Crab, Panopeus-Herbstii, Frank O. Perkins
Fine-Structure Of Minchinia Sp (Haplosporida) Sporulation In Mud Crab, Panopeus-Herbstii, Frank O. Perkins
VIMS Articles
Morphogenetic changes which accompany sporulation of Minchinia sp. in the mud crab (Panopeus herbstii) are described. Small (4-19 /-1m diameter) plasmodia, the precursor cells for the sporulation sequence, increase in size and numbers of nuclei per cell to form sporonts with a delimiting wall. Since widely divergent nuclear sizes (2.3-5.9 /-1m diameter) and paired small nuclei < 3 /-1m diameter) were observed in sporonts, it is suggested that karyogamy occurs followed by meiosis. Evidence for meiosis is the observation of synaptonemal-like complexes and polycomplex-like structures in sporont nuclei. Sporonts cleave into uninucleate sporoblasts following one of two pathways. In the presumably "normal" sequence, a cytoplasmic syncytium is formed followed by cleavage into uninucleate sporoblasts. In the other, sporont protoplasm is asynchronously "carved" into uni- or binucleate sporoblasts or sporoplasms as a result of delimitation at the surface and internally. Since aberrant spore formation was commonly observed in the latter type of sporont, its cleavage patterns are considered to be anomalous. A sporoplasm is then delimited in each sporoblast and spore maturation follows. Haplosporosomes were observed in plasmodia and spores, but not in intermediate cell stages. Mitotic apparati appear to be persistent through interphase in plasmodia and sporonts and consist of two spindle pole bodies connected by a bundle of micro tubules.
Two New Species Of Sciaenid Fishes (Tribe-Sciaenini) From Caribbean Sea And Adjacent Waters, Ln Chao, Rv Miller
Two New Species Of Sciaenid Fishes (Tribe-Sciaenini) From Caribbean Sea And Adjacent Waters, Ln Chao, Rv Miller
VIMS Articles
The genus Sciaena , heretofore monotypic, is characterized by the lack of mental barbels and an elongate swimbladder with no appendages. Two new species S. trewavasae and S. bathytatos are described herein. The new species differ from S. umbra, the type species of the genus, and from one another in the following characters: S. umbra has 11 + 14 vertebrae, 15-20 gill rakers, 23-26 soft dorsal rays, 9-13 inner gill rakers; S. trewavasae has 10 + 15 vertebrae, 19-21 gill rakers, 24-26 soft dorsal rays, 13-16 inner gill rakers; S. baillylalos has 11 + 14 vertebrae, 22-27 gill rakers, 21-23 …
The Hyperparasite, Urosporidium Spisuli Sp. N. (Haplosporea), And Its Effects On The Surf Clam Industry, Frank O. Perkins, D. E. Zwerner, Robert K. Dias
The Hyperparasite, Urosporidium Spisuli Sp. N. (Haplosporea), And Its Effects On The Surf Clam Industry, Frank O. Perkins, D. E. Zwerner, Robert K. Dias
VIMS Articles
SSurf clams (Spisula solidissima) from along the Virginia and North Carolina coasts are infected with an immature anisakid nematode worm which does not cause economic concern until infected with the protozoan hyperparasite, Urosporidium spisuli sp. n. When the protozoan sporulates the spores give the worm a brownish-black appearance, thus making it readily visible in clam tissues. Light and electron microscope studies of the spores reveal characteristics which differentiate the protozoan from other species of Urosporidium. All spores are killed after 5 to 30 min at 100 C; therefore, the consumer would not ingest live spores when eating commercially prepared clam …
Reproduction And Recruitment Of The Brackish Water Clam, Rangia Cuneata In The James River, Virginia, Thomas D. Cain
Reproduction And Recruitment Of The Brackish Water Clam, Rangia Cuneata In The James River, Virginia, Thomas D. Cain
VIMS Articles
Reproduction and recruitment of the brackish water clam Rangia cuneata were investigated in the James River, Va., from February 1970 to January 1972. Histological examinations of gonads were made, newly set clams were collected, and temperature and salinity measurements were taken from three populations living in different salinity regimes.