as new pathogenic strains are emerging and threatening aquaculture development, myxosporeans (myxozoa) are receiving much attention in recent years. myxosporean taxonomy is traditionally based on morphology of the myxospore stage. molecular data on indian myxosporeans are rare. in this report, the 18s rrna gene sequence of myxobolus cuttacki infecting gill lamellae of minor carp labeo bata (ham...

Epithelial plasma membranes from crustacean gut, kidney and gills have been shown recently to display an electrogenic 2Na+/1H+ antiporter that differs considerably in its physiological properties from the vertebrate electroneutral 1Na+/1H+ exchange paradigm. In this study, we describe the histological and cytological localization of an antigen associated with invertebrate electrogenic 2Na+/1H+ ...

Inanga (Galaxias maculatus) are a euryhaline and amphidromous Southern hemisphere fish species inhabiting waters highly contaminated in trace elements such as nickel (Ni). Ni is known to exert its toxic effects on aquatic biota via three key mechanisms: inhibition of respiration, impaired ion regulation, and stimulation of oxidative stress. Inanga acclimated to freshwater (FW), 50% seawater (SW...

Using reverse transcription-PCR and molecular cloning, the complementary DNA sequence encoding preproinsulin-like growth factor I (IGF-I) of a teleost, the tilapia (Oreochromis mossambicus) was established from liver. At the amino acid level, tilapia IGF-I shows all residues necessary for the maintenance of tertiary structure and shares about 80% identity with IGF-I from other teleosts. The B a...

This study evaluates the effects of different levels of guanidinoacetic acid (GAA) supplement on growth performance and gut morphology in broilers (Ross 308 strain) raised at high altitude (2100 m). A total of 300 one-day-old male broiler chicks (Ross 308 strain) were used in a completely randomized design with five treatments and four replicate pens of 15 birds in each. Five dietary treatments...

While a large respiratory surface area is good for gas exchange, it also poses several problems, including energetically unfavorable fluxes of water and ions. As a result, fishes appear to have a respiratory surface area that is matched to their oxygen demands. When faced with changes in their need for oxygen uptake, e.g. through altered physical activity or altered ambient oxygen levels, fishe...

The accumulation of metal in soft tissues, filtration rate and gill filament morphology are correlated in the southern African rock mussel, Perna perna, during exposure to mercury (24 days) and recovery (24 days). The amount of Hg in soft tissues increased from 0.13 to 87.5 microg/g dry weight after 24 days exposure, and declined to 13 microg/g during recovery. Mean filtration rate fell from 3,...

Background: Many theoretical models of speciation and niche evolution assume that the ecological similarity between conspecific individuals depends on their phenotypic similarity. Thus, competition between individuals is expected to depend on their phenotypic similarity. Theoretical models often assume that this intraspecific competition function is Gaussian. Questions: Are morphological simila...