Effects of Confluent, Roscovitine Treatment and Serum Starvation on the Cell-cycle Synchronization of Bovine Foetal Fibroblasts

The present study was designed to examine the effects of cell-cycle synchronization protocols, such as confluent, roscovitine treatment and serum starvation, in bovine foetal fibroblasts on synchronization accuracy at G0/G1, viability, apoptosis, necrosis and ploidy for use as a nuclei donor. The cells in 5-10 passages were randomly allocated into three treated groups. Cells were cultured either in Dulbecco's modified Eagle's medium (DMEM) + 10% foetal bovine serum (FBS) until 90% confluent (group 1, confluent), in DMEM + 10% FBS + 30 microM roscovitine for 12 h (group 2, roscovitine), or in DMEM + 0.5% FBS for 5 days (group 3, serum starvation). Most of the cells (>80%) in all groups were arrested at the G0/G1 stage. Although the rates did not differ, cells in group 1 showed an increased cell population arrested at the G0/G1 phase. Significantly (p < 0.05) higher rates of apoptosis occurred in group 3 than in group 1 and 2 (10% vs 6% and 6%, respectively). No differences in chromosomal abnormality were observed among groups. However, by increasing the number of cell culture passages up to 15, significantly (p < 0.05) higher chromosomal abnormality was observed than in 5 and 10 passages (39% vs 28% and 23%, respectively) in group 1. The results clearly indicated that bovine foetal fibroblasts could be effectively synchronized at G0/G1 stages by all the three different treatments, confluent, roscovitine and serum starvation. However, cells in confluent showed reduced apoptosis and necrosis when they underwent 5-10 passages, exhibiting increased percentage of cells with stable chromosome diversity. Hence, cells in confluent merit further studies before they could be used as nuclear donors.     

Pectate lyases of Erwinia chrysanthemi: Pel E-like polypeptides and pelE homologous sequences in strains isolated from different plants

Pel E, one of the four major pectate lyases produced by Erwinia chrysanthemi (Echr) strain EC16, was purified to homogeneity and was found to have an apparent molecular weight of 47 500 and a pI of 10. Antibodies produced against this preparation inhibited Pel E activity, but did not affect Pel A, Pel B or Pel C activities. Immunotitration revealed that Pel E accounted for a major fraction of the total extracellular Pel activity ranging from 40–60% in culture and potato tuber tissue. Isoelectric focusing of the extracellular Pels produced by various Echr strains indicated that while the Pel profiles of strains isolated from various hosts were different, the profiles of strains isolated from the same host were very similar. A significant proportion (ranging from 39 to 74%) of the Pel activity of these strains was inhibited by the anti-Pel E antibodies. DNA hybridization under stringent conditions indicated the presence of pelE homologous sequences in the genomes of E. chrysanthemi strains. We conclude that a Pel E-like enzyme occurs in all E. chrysanthemi strains examined.     

ELLA: A Rapid Technique to Estimate Chromium Stress-Induced Modification of E. coli EI19

An enzyme-linked lectin assay (ELLA) was used to differentiatebetween chromium-stressed and unstressed cells of Escherichia coli EI19. The assay is a modification of the enzyme-linked immunosorbent assay (ELISA) that uses Concanavalin A (Con A) conjugated with peroxidase to detect the carbohydrate moiety of the cell envelope glycoconjugates. The ELLA test shows that Con A binds to stressed bacteria much moreefficiently than it does to unstressed bacteria. Effects of heat,phenol and papain treatments on Con A-binding to chromium-stressed bacteria were also studied. Con A-binding to bacteria was sensitive to heat and phenol treatment, but not to treatment with papain. A potential analytical method for estimating the concentration of certain environmental pollutants is outlined.     

Economic Impact of Double‐Crested Cormorant,Phalacrocorax auritus,Depredation on Channel Catfish,Ictalurus punctatus,Aquaculture in Mississippi,USA

The Yazoo River Basin of Mississippi, USA, supports the largest concentration of hectares devoted to channel catfish, Ictalurus punctatus, aquaculture production in North America. The Yazoo Basin also supports large numbers of resident, wintering and migrating fish‐eating birds, with the Double‐crested Cormorant, Phalacrocorax auritus, implicated as the most serious depredating species. We used data from aerial surveys of numbers and distribution of cormorants in the Yazoo Basin and on commercial catfish ponds during winters (November–April) 2000–2001 and 2003–2004 to refine estimates of regional economic losses due to cormorant depredation. In both periods, the greatest monthly estimates of cormorant foraging occurred from 1 January to 31 March. Losses in terms of biomass, number, and dollar value were greater for foodfish ponds than fingerling ponds. Monthly weighted estimates of catfish consumed were 1775.3 and 1346.6 m.t. over winters 2000–2001 and 2003–2004, respectively. Total estimated losses for foodfish and fingerling ponds in 2000–2001 were $11.56 and $0.48 million, respectively, and in 2003–2004 were $5.22 and $0.40 million, respectively. Maximum dollar loss occurred during March in 2000–2001 and during February in 2003–2004. In this study, the volatility in variable production costs and nominal sales price, and distribution of cormorants on pond types and regionally were key factors in resulting economic loss estimates.     

Effects of ivermectin and fenbendazole in strategic treatment of gastrointestinal nematode infections in cattle

Four groups of 18 beef calves each were used to evaluate effects of different treatments on parasite control and weight gains. The investigation extended from November 1986 (weaning) to October 1987. Group-1 calves were treated with ivermectin (200 micrograms/kg of body weight, SC) at approximately 6-week intervals for a total of 8 treatments; group-2 calves were given the same dosage of ivermectin by the same route of administration as group-1 calves in November, March, and July; group-3 calves were given fenbendazole paste (5 mg/kg, PO) at the same times as group-2 calves; and group-4 calves served as untreated controls with provision for ivermectin salvage treatment. All groups grazed on individual pairs of larval-contaminated, 1.6-ha pastures. Highest (P less than 0.05) initial worm counts in fall tracer calves were found in group 3 (Ostertagia ostertagi and Trichostrongylus axei adults) and group 4 (O ostertagi and Haemonchus adults). Fecal egg counts of group-1 calves were low throughout the experiment and pasture larval counts remained negligible after July. Egg counts and larval counts of other groups remained higher into summer. Worm counts, including O ostertagi inhibited early fourth-stage larvae (EL4), were highest (P less than 0.05) in groups-3 and -4 spring tracer calves; numbers of O ostertagi EL4 were similarly high in groups 2, 3, and 4; and T axei counts were highest (P less than 0.05) in groups-3 and -4 yearlings slaughtered in spring. Liveweights of group-1 calves were greater (P less than 0.05) than in other groups from March 2 to October, and by July 2, group-2 calves had a liveweight advantage over group-4 calves. Group-3 calves had the lowest rate of gain from March to July and mean liveweight of the group was less (P less than 0.05) than in all other groups from April to October. Only minimal worm numbers were recovered from groups-1 or -2 calves in October. Large numbers of O ostertagi and T axei were recovered from group-4 calves and O ostertagi from group-3 calves. A few calves in groups 3 and 4, but particularly in group 4, were affected by type-II disease (chronic to acute gastritis caused by maturation and emergence of previously inhibited larvae) from August to October. Final mean liveweights in descending order were 365 kg in group 1, 328 kg in group 2, 316 kg in group 4, and 281 kg in group 3.