Use of PCR-RFLP Analysis of mtDNA Cytochrome-b Gene to Determine Genetic Differences in Capoeta spp.

Genetic differences between Capoeta capoeta capoeta, Capoeta capoeta umbla, and Capoeta tinca were determined using PCR-RFLP of mtDNA cytochrome-b (Cyt-b) by amplifying approxi- mately 400-500 bp of this region from each of the three subspecies. The restriction enzymes SpeI and HinfI did not indicate genetic differences but AluI and HpaII did. Thus, PCR-RFLP of the mtDNA was used to distinguish between closely related subspecies without having to ana- lyze the entire DNA sequence of specimens. Use of this technique demonstrated that the Cyt-b regions of the three subspecies have different base sequences. The similarity between C. c. capoeta and C. c. umbla is 71.4% while C. tinca is more distant (50% for C. c. umbla and 33.3% for C. c. capoeta). The Cyt-b similarity is consistent with morphological and taxonomical similar- ities. PCR-RFLP can serve as a tool for genetically identifying subspecies of fish in nature and in aquaculture

Alterations in Hematological Parameters of Rainbow Trout (Oncorhynchus mykiss) Exposed to DDVP

The aim of this study was to assess the effects of a sublethal dose (1.6 mg/l) of DDVP (dichlor- vos) on hematological parameters of rainbow trout (Oncorhynchus mykiss) after 28 days of exposure. The DDVP caused increases in the red and white blood cell counts, hemoglobin, ery- throcyte sedimentation rate, mean corpuscular volume, and mean corpuscular hemoglobin con- centration (MCHC). On the other hand, it decreased thrombocyte (Plt), hematocrit (packed cell volume), and mean corpuscular volume. The only statistically significant differences between exposed and unexposed fish were in white blood cell count and MCHC

Authentication of fish species using a simple PCR-RFLP method

A polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method was developed as a tool to prevent commercial frauds in fish products. The PCR was used to ampli- fy the cytochrome b gene, part of the mitochondrial genome. The PCR products were digested with different restriction endonucleases (AluI, HaeIII, HinfI, Hsp92, Taql) to identify five fish species - Mugil cephalus, Pomatomus saltator, Belone belone, Merlangius merlangus, and Oncorhynchus mykiss. None of the tested enzymes, alone, was able to distinguish between the five fish species, but by combining the results of two digestions, all five species could be differ- entiated. Thus, this method can be used to expose fraudulent substitutions with less valuable fish

Effects of 2,2-Dichlorovinyl Dimethyl Phosphate (DDVP) on Hsp70 Gene Expression in Rainbow Trout

2,2-Dichlorovinyl dimethyl phosphate (DDVP) is used to control insects on crops, household, and stored products, and treat external parasitic infections in farmed fish, livestock, and domestic animals. Ectoparasitic copepods can cause severe skin damage in fish that may lead to death through osmoregulatory failure or infection by opportunistic pathogens. There is considerable uncertainty about whether or not DDVP is implicated in cancer, and the wider environmental con- sequences of its use. In general, and specifically in developing countries and fish farming, less hazardous alternatives are available. The present experiment studied the effects of DDVP at a daily dose of 1.6 mg/l for 21 days on the expression of the heat shock protein (Hsp) 70 gene in rainbow trout (Oncorhynchus mykiss). Hsp70 from control and DDVP-exposed fish was ampli- fied for 20-40 PCR cycling. After the fortieth PCR cycle, the Hsp70 level in mRNA was very low in the control fish and very high in the DDVP-exposed fish, with a statistical difference of p<0.01