Induction of mitotic and meiotic gynogenesis and production of genetic clones in rohu, Labeo rohita Ham.

Studies were undertaken to produce genetic clones derived from all homozygous mitotic gynogenetic individuals in rohu, Labeo rohita Ham. ln view of this, attempts were made to interfere with the normal functioning of the spindle apparatus during the first mitotic cell division of developing eggs using heat shocks, there by leading to the induction of mitotic gynogenetic diploids in the F1 generation. Afterwards, viable mitotic gynogenetic alevins were reared and a selected mature female fish was used to obtain ovulated eggs which were fertilized later with UV-irradiated milt. Milt was diluted with Cortland’s solution and the sperm concentration was maintained at 10⁸/ml. The UV-irradiation was carried out for 2 minutes at the intensity of 200 to 250 µW/cm² at 28± 1°C. The optimal heat shock of 40°C for 2 minutes applied at 25 to 30 minutes a.f. was used to induce mitotic gynogenesis in first (F1) generation and at 3 to 5 minutes a.f. to induce meiotic gynogenesis in the second (F2) generation. The results obtained are presented and the light they shed on the timing of the mitotic and meiotic cell division in this species is discussed.

Field applications of the second-generation Environmental Sample Processor (ESP) for remote detection of harmful algae: 2006-2007

We assess the application of the second-generation Environmental Sample Processor (ESP) for the detection of harmful algal bloom (HAB) species in field and laboratory settings using two molecular probe techniques: a sandwich hybridization assay (SHA) and fluorescent in situ hybridization (FISH). During spring 2006, the first time this new instrument was deployed, the ESP successfully automated application of DNA probe arrays for various HAB species and other planktonic taxa, but non-specific background binding on the SHA probe array support made results interpretation problematic. Following 2006, the DNA array support membrane that we were using was replaced with a different membrane, and the SHA chemistry was adjusted. The sensitivity and dynamic range of these modifications were assessed using 96-well plate and ESP array SHA formats for several HAB species found commonly in Monterey Bay over a range of concentrations; responses were significantly correlated (p < 0.01). Modified arrays were deployed in 2007. Compared to 2006, probe arrays showed improved signal:noise, and remote detection of various HAB species was demonstrated. We confirmed that the ESP and affiliated assays can detect HAB populations at levels below those posing human health concerns, and results can be related to prevailing environmental conditions in near real-time.