Presence of Ureaplasma diversum in the Australian cattle population.

In cattle, Ureaplasma diversum has been associated with decreased fertility, granular vulvovaginitis, endometritis, salpingitis and spontaneous abortion in cows and seminal vesiculitis, balanoposthitis and changes in bull sperm. The presence of U. diversum within the Australian cattle population has not been established. One of the aims of this study was to determine if U. diversum was present in Australian cattle, using culture and polymerase chain reaction (PCR), both of which are considered to be gold standards for bacterial identification. Of 100 samples collected from 66 male and 34 female cattle, 15 were positive for U. diversum. Therefore, Australia can no longer be considered free of U. diversum. Further studies should be conducted to ascertain the effects of U. diversum within Australian cattle herds and, if warranted, to investigate prevention, treatment and eradication protocols.

Predator Avoidance of Transgenic Channel Catfish Containing Salmonid Growth Hormone Genes.

Transgenic channel catfish (Ictalurus punctatus) containing salmonid growth hormone genes can grow 33% faster than normal channel catfish under aquaculture conditions. However, before transgenic catfish are released and utilized by the private sector, their genetic impact on the natural environment must be examined. Predator avoidance is one of the major fitness traits determining potential environmental risk. To determine the predator avoidance ability and growth performance of transgenic catfish in a natural habitat, various densities of transgenic and nontransgenic channel catfish were communally stocked in 0.04-ha earthen ponds without supplemental feeding. Largemouth bass (Micropterus salmoides) and green sunfish (Lepomis cyanellus) were stocked as predators. Nontransgenic fry had better predator avoidance than transgenic channel catfish when data were pooled (p <.01). When data were not pooled, nontransgenic catfish had better predator avoidance in six trials and transgenic individuals had better predator avoidance in four trials. There was no difference in predator avoidance in three trials. Overall predator avoidance was also better for nontransgenic individuals (p <.01) when the fish were evaluated as 3.5-g fingerlings, more clearly than as fry, as transgenic individuals were more vulnerable in 3 of 4 trials at this life stage. There was no significant difference in growth performance between transgenic and nontransgenic channel catfish in ponds without supplemental feeding. These findings indicate that transgenic channel catfish could be used for commercial aquaculture without affecting the natural environment. Although transgenic channel catfish may be released to nature by accident, any ecological effect would be unlikely because the increased susceptibility of transgenic channel catfish to predators would most likely decrease or eliminate the transgenic genotype.

Gonadotropin alpha-subunit glycoprotein from channel catfish (Ictalurus punctatus) and its expression during hormone-induced ovulation.

Complementary DNA (cDNA) encoding the channel catfish (Ictalurus punctatus) gonadotropin (GTH) alpha-subunit glycoprotein was cloned by polymerase chain reaction (PCR) from a plasmid library made from pituitary RNA. Complete cDNA cloning was achieved by carrying out two PCR reactions: one with an upstream sense primer plus the universal sequencing primer, located downstream of the poly(A) sequence of the cDNA in the plasmid vector, to amplify the downstream portion of the cDNA; the other with a downstream antisense primer plus the reverse-sequencing primer, located upstream of the very 5' end of the cDNA sense strand in the plasmid vector, to amplify the upstream portion of the cDNA. The two amplified fragments overlapping about 70 bp. Nucleotide sequence analysis revealed that the catfish GTH alpha-subunit was 658 bp encoding 116 amino acids and harboring a 5' nontranslated region (NTR) of 42 bp and a 3' NTR of 265 bp. The deduced amino acid sequence of the catfish GTH alpha-subunit is highly conserved with those from other cloned teleost GTH alpha-subunits. The GTH alpha-subunit was highly expressed even before induction for ovulation in females during spawning season. Administration of carp pituitary extract (a spawning-inducing reagent) induced only 1.4-fold higher expression of the GTH alpha-subunit RNA, but included very rapid egg maturation and ovulation. This unexpected result indicated that the GTH alpha-subunit may not be the limiting factor for ovulation and spawning, which may be regulated by the change of proportional coupling of the GTH alpha-subunit with specific beta-subunit during hormone-induced ovulation.