Influence of Bordetella avium infection on association of Escherichia coli with turkey trachea

Four-week-old Bordetella avium-infected and B avium-free turkeys were inoculated intratracheally with a suspension of fimbriated or nonfimbriated Escherichia coli. Numbers of E coli associated with tracheal sections were determined at postinoculation hour (PIH) 1 or 6. Significantly (P less than 0.05) greater numbers of E coli were isolated from the tracheas of B avium-infected turkeys compared with numbers in B avium-free turkeys. In B avium-free turkeys, tracheal associated E coli were 90% less at PIH 6 compared with that at PIH 1. However, in B avium-infected turkeys, numbers of E coli were not affected by postinoculation time. Seemingly, B avium-infected turkeys had reduced capacity to clear E coli from the trachea.     

A diiron protein autogenerates a valine-phenylalanine cross-link

All known internal covalent cross-links in proteins involve functionalized groups having oxygen, nitrogen, or sulfur atoms present to facilitate their formation. Here, we report a carbon-carbon cross-link between two unfunctionalized side chains. This valine-phenyalanine cross-link, produced in an oxygen-dependent reaction, is generated by its own carboxylate-bridged diiron center and serves to stabilize the metallocenter. This finding opens the door to new types of posttranslational modifications, and it demonstrates new catalytic potential of diiron centers.     

An evaluation of anthelmintic properties,assessed using faecal nematode egg counts,of New Zealand native flax (Phormium tenax)

AIM: To investigate the anthelmintic properties of New Zealand native flax (Phormium tenax) for cattle, using a faecal egg count reduction test (FECRT).

METHODS: Twenty-six heifer calves with high (>300 epg) faecal nematode egg counts (FEC) were paired into two groups and fed either chopped flax leaves ad libitum, or barley straw at an equivalent dry matter (DM) rate, from Day 0–7; all were supplemented with 1.5 kg/head/day cereal feed supplement. On Days 8–10, all heifers were fed a common diet of 3.5 kg DM/ head/day barley straw and 1.5 kg/head/day cereal feed supplement. Heifers were weighed and faecal samples were collected on Days —6, 0, 7, and 10; samples were analysed in triplicate for FEC. The nutritive value of the flax and straw was analysed.

RESULTS: Both the flax and straw had low dry matter digestibility (DMD) and protein content. Although the flax-fed claves grew more than the controls, this may have been related to gut fill. Total daily faecal egg output was similar for flax and straw groups on Day 7 (14.7 vs 15.0 x 10⁶ eggs/day, respectively) and Day 10 (14.9 vs 15.1 x 10⁶ eggs/day, respectively). There was no difference in the change in FEC with time between the calves fed flax or straw diets.

CONCLUSION: Consumption of flax leaves did not reduce FEC in calves with a mixed nematode infection.     

Antimicrobial Resistance in Some Gram‐Negative Bacteria Isolated from the Bovine Ejaculate

The bacterial load and degree of antibiotic resistance present in untreated and antibiotic‐treated semen samples were investigated in five bulls standing at a cattle‐breeding centre. Bacterial load was determined by colony counts from semen samples cultured on brain heart infusion and nutrient agar plates. Antibiotic resistance in these bacteria was assessed by measuring the diameter of bacterial growth inhibition zones around discs containing different concentrations of antibiotics. Representative antibiotic‐resistant bacterial isolates were selected for identification. Untreated semen contained few culturable bacteria, and all were completely sensitive to gentamycin, spectinomycin and lincomycin: six of the isolates showed some resistance to tylosin. In semen to which antibiotics had been added as part of the routine production process, two isolates were sensitive to all of the antibiotics tested, and the remainder were resistant to all. Resistant Gram‐negative isolates that were identified included Pseudomonas and Stenotrophomonas spp. both in the class Gammaproteobacteria and a Sphingomonas sp. which is in the class Alphaproteobacteria.     

Robust reconstitution of active cell-cycle control complexes from co-expressed proteins in bacteria

ABSTRACT: BACKGROUND: Cell proliferation is an important determinant of plant growth and development. In addition,modulation of cell-division rate is an important mechanism of plant plasticity and is key inadapting of plants to environmental conditions. One of the greatest challenges inunderstanding the cell cycle of flowering plants is the large families of CDKs and cyclins thathave the potential to form many different complexes. However, it is largely unclear whichcomplexes are active. In addition, there are many CDK- and cyclin-related proteins whosebiological role is still unclear, i.e. whether they have indeed enzymatic activity. Thus, abiochemical characterization of these proteins is of key importance for the understanding oftheir function. RESULTS: Here we present a straightforward system to systematically express and purify active CDKcyclincomplexes from E. coli extracts. Our method relies on the concomitant production of aCDK activating kinase, which catalyzes the T-loop phosphorylation necessary for kinaseactivity. Taking the examples of the G1-phase cyclin CYCLIN D3;1 (CYCD3;1), the mitoticcyclin CYCLIN B1;2 (CYCB1;2) and the atypical meiotic cyclin SOLO DANCERS (SDS) inconjunction with A-, B1- and B2-type CDKs, we show that different CDKs can interact withvarious cyclins in vitro but only a few specific complexes have high levels of kinase activity. CONCLUSIONS: Our work shows that both the cyclin as well as the CDK partner contribute to substratespecificity in plants. These findings refine the interaction networks in cell-cycle control andpinpoint to particular complexes for modulating cell proliferation activity in breeding.