The Eurasian amphipod Echinogammarus ischnus is reportedly replacing the common native amphipod Gammarus fasciatus in the Great Lakes – St. Lawrence River system. A potential mechanism for this replacement is competition mediated by resident species. Other Eurasian invaders, dreissenid mussels (Dreissena polymorpha and Dreissena bugensis), dominate rocky substrates throughout the system and mig...

T HE object of this investigation was to measure simultaneous changes in blood pressure and blood flow in the pulmonary circulation of the intact dog. Observations were made during standing and running at different rates on a treadmill. A further group of dogs subjected recently to ligation and division of the left pulmonary artery was studied also. This permitted an extension of the observatio...

A total of 18 isolates of Edwardsiella tarda was successfully isolated from African Catfish (Clarias gariepinus), Red Hybrid Tilapia (Tilapia sp.), Asian Swamp Eel (Monopterus albus) and Snakeskin Gouramy (Trichogaster pectoralis). The percentage similarity of phenotypic, genotypic and proteotypic characteristics of the present isolates was ranged from 80.8 to 100%, 27.9 to 89.4% and 46.3 to 10...

Structural inheritance in the ciliate cortex. Ciliates make up a distinctive group of unicellular organisms characterized by dualism of germ line and somatic nuclei, sex by reciprocal exchange of gametic nuclei with subsequent replacement of the somatic nucleus, and an extraordinarily complex organization of the cell surface layer. This organization is dominated by cytoskeletal structures, incl...

Wallinia chavarriae n. sp. is described from the small-bodied characids Astyanax aeneus and Bryconamericus scleroparius in the Area de Conservacion Guanacaste, northwestern Costa Rica. The species differs from W. valenciae in possessing an acetabulum that is smaller than the oral sucker and vitelline follicles that are ovoid or rounded rather than elongate and tubular. Detailed comparison betwe...