Abstract Mercury (Hg) is a heavy metal that commonly found in waters and sediments. its derivatives are highly toxic ) . Their presence the aquatic environment can be very detrimental. Aspergillus fungi known to reduce Hg levels pollutants. Our research aim was evaluate effect of after being reduced by local isolates Penicillium sp. strain A4. A toxicity test conducted on juvenile Caroline plat...

vigorous immune response against tissue homografts is characteristic of A nearly all postembryonic vertebrates. The homograft reaction has been demonstrated in all species of teleosts tested (KALLMAN 1964; HILDEMANN and HAAS 1960), and in many amphibians (HILDEMANN and HAAS 1959; VOGEL 1940; HOROWITZ 1937), in at least one reptile (MAY 1923), several birds (HEALEY, RUSSEL, POOLE and OLSEN 1962;...

The classic works of Noble (1939), Noble & Borne (1940) and Braddock (1945, 1949) have shown that small isosexual and heterosexual groups of Xiphophorus fish form hierarchies based upon dominance submission relations which are established by challenging and fighting. The resulting dominance orders show a tendency toward the straight line type, although incomplete hierarchies and intransitive tr...