Molecular genetics and the initiation of solventogenesis in Clostridium beijerinckii (formerly Clostridium acetobutylicum) NCIMB 8052

A physical map of the Clostridium beijerinckii (formerly Clostridium acetobutylicum) NCIMB 8052 chromosome has been constructed, encompassing about 90 rare restriction sites. The 14 rrn operons together with about 40 genes have been assigned positions on the map. Genetic analysis and gene transfer have been developed in this organism to enable in vivo analysis of the roles of cloned genes using marker replacement technology. Experiments using the available genetic tools have shown that spo0A plays a cardinal role in controlling several aspects of the transition from exponential growth to stationary phase in C. beijerinckii. These include initiation of sporulation, accumulation of the storage polysaccharide, granulose, and production of acetone and butanol. Several C. beijerinckii and C. acetobutylicum genes concerned with fermentative metabolism, whose expression is modulated at the onset of solventogenesis, contain sequence motifs resembling 0A boxes in their 5' regulatory regions. This invites the speculation that they are under the direct control of Spo0A, and additional data are now required to test this prediction.

Physical map of the Clostridium beijerinckii (formerly Clostridium acetobutylicum) NCIMB 8052 chromosome

A combined physical and genetic map of the single, circular, 6.7-Mbp chromosome of the NCIMB 8052 strain of Clostridium beijerinckii (formerly Clostridium acetobutylicum) has been constructed by using a combination of cloned DNA fragments as hybridization probes and a bank of strains harboring insertions of the conjugative transposon Tn1545. The positions of 81 restriction endonuclease cleavage sites and 32 genes have been determined. Eight genes concerned with solventogenic fermentation are found at three different locations. The chromosome contains at least 13 rrn operons, 11 of which have been located on the map. Their transcriptional orientation diverges from the presumed location of the replication origin.

Characterization of spo0A homologues in diverse Bacillus and Clostridium species identifies a probable DNA-binding domain

Spo0A is a phosphorylation-activated transcription factor of Bacillus subtilis. It is a member of the response regulator superfamily of bacterial signal transduction proteins and controls many of the changes in gene expression that occur during the transition into stationary phase and during the initiation of sporulation. To identify the domains of Spo0A most critical for determining its structural and functional features, presumptive homologues of the spo0A gene were characterized in a collection of eight Bacillus species and six Clostridium species representing phylogenetically diverse members of these genera. An alignment of the partial or complete DNA sequences of these homologues revealed three regions of especially high conservation in the effector domain. We speculate that the most highly conserved of these corresponds to the recognition helix of a putative helix-turn-helix motif, and, therefore, represents the actual DNA-containing surface of the protein. In the case of homologues identified in Bacillus anthracis and Clostridium acetobutylicum and retrieved by polymerase chain reaction amplification, we confirmed by gene-disruption analysis that the homologue actually is required for initiation of sporulation. Apparent homologues of the B. subtilis spoIVB gene were also discovered immediately upstream from the spo0A homologues in all Bacillus and Clostridium species examined. The discovery of homologues of B. subtilis sporulation genes in these diverse species implies that the gene products required for specifying pathways of sporulation-specific gene activation and for determining key morphogenetic changes may be highly conserved and suggests that an approach similar to that undertaken here might be used as a general strategy to retrieve and compare their gene sequences. Exhaustive efforts to detect a spo0A-like gene in non-endospore formers, including close relatives of Bacillus such as Listeria and Staphylococcus, were uniformly unsuccessful, suggesting that regulation of gene activity during the transition into stationary phase mediated by Spo0A-like proteins may be exclusive to the endospore-forming bacteria.

[Child psychiatry at a general hospital. The aims of preventive "liaison child psychiatry"]

The department of child psychiatry, Ullevål Hospital, has started a liaison child psychiatry service for persons under 18 years old admitted to the hospital. The different tasks involved are analysed with a view to meeting the requirements of the different wards. This facilitates purposeful liaison, establishment of jointly agreed priorities and evaluation of the service.

Germs. Nursery school children's views on the causality of illness

A study of Scottish nursery school children shows how they construct their world of illness using the images provided in the nursery and home. An awareness of children's perceptions of the world of illness enables professionals to establish helpful clinical relationships. The ways in which children handle images and respond to the questions of adults suggest that health education strategies should be reviewed.

Evaluation of the morantel sustained release bolus in cows and calves

The efficacy of the morantel sustained release bolus (MSRB) in controlling gastrointestinal parasitism in beef cattle was assessed during the 1982 spring-autumn grazing season. Forty-eight cows and their calves were allotted to three equal groups. One group (T-1) served as a nonmedicated control group. One MSRB was administered to each calf of the T-2 group, and to each cow and calf of the T-3 group at the beginning of the study. The efficacy of the bolus was assessed by comparison of weight gain performance and parasitological data (fecal worm egg counts, herbage larval counts, worm counts from tracer and principal trial calves, and plasma pepsinogen level determinations). Though not statistically significant, treated calves from Group T-2 had a numerical mean weight gain advantage of 2.6 kg, and those from Group T-3 of 4.7 kg, over control calves. Average daily gains (ADG) for the three groups of calves were 0.69, 0.72, and 0.73 kg, respectively. Untreated cows from Group T-2 and treated cows from Group T-3 outperformed the control cows by 12.3 and 7.5 kg, respectively. Fecal worm egg counts from both groups of treated calves were significantly (P less than 0.01) lower than counts from control calves during the entire 169-day trial; notably, egg counts were reduced by 99% 28 days after MSRB administration to both groups of calves. There were no significant differences in the number of eggs counted from the three groups of cows, probably because of the very low numbers of eggs encountered. Mean total worm burdens of principal calves (six per group) necropsied at trial termination indicated a 91% (P less than 0.01) reduction in Group T-2 and an 87% reduction (P less than 0.01) in Group T-3. Worm-free tracer calves were introduced onto pastures every 28 days to monitor availability of infective larvae. The mean number of worms recovered at necropsy from tracer calves that grazed with control cattle increased as the season progressed. However, the numbers of parasites recovered each month from mid-August through mid-October from tracers that grazed pastures with treated cattle were lower (P less than 0.05) than those levels displayed at trial initiation. In addition, the mean numbers of worms from treated group tracers were lower than from the controls for each necropsy period.(ABSTRACT TRUNCATED AT 400 WORDS)

Association of blood cholesterol with occurrence of fat necrosis in cows and tall fescue summer toxicosis in steers

Factors associated with fat necrosis in cows and tall-fescue summer toxicosis in steers were studied. In the cow study, fescue pastures were fertilized, using 3 rates of N: high N (703 to 483 kg and 0 kg of N/ha/year from broiler litter in 1972 to 1974 and 1975, respectively), moderate N, and low N (224 and 74 kg of N/ha/yr from NH4NO3, 1972 to 1975, respectively). Bermuda grass pastures were fertilized at 2 rates of N: moderate N and low N (280 and 20 kg of N/ha/year from NH4NO3, 1972 to 1975, respectively). Fat necrosis developed only in cows grazing tall fescue, with an occurrence of 60%, 8%, and 3% for high-N, moderate-N, and low-N pastures, respectively. Cows grazing the high-N fescue, and to some extent those grazing the moderate-N fescue, had clinical signs of summer fescue toxicosis. Plasma cholesterol concentrations were lowest in cattle grazing the high-N fescue, averaging 114 mg/dl, followed by 134 and 127 mg/dl in cattle grazing the moderate-N and low-N fescue, respectively. In the steer grazing study, 24 paddocks of 0.49 ha each were seeded with tall-fescue lines G1-307 or G1-306 or with tall-fescue cultivars, KY-31 or Kenhy. All paddocks were fertilized with 170 kg of N/ha/year. Serum cholesterol concentrations were lower in steers grazing on G1-307 than in steers grazing on G1-306 or cultivars. Serum total lipids followed a similar trend, with a positive correlation (r = 0.49) between cholesterol and total lipids.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of a once-daily suckling program on gastrointestinal parasitism in Angus cows and calves

Over a 2-year period involving a total of 168 Angus cows and their calves, 2 studies were conducted to evaluate the effect of once-daily suckling on cow reproduction, calf growth, and gastrointestinal parasitism. Experiment I compared 2 restricted suckling (RS) groups with 1 normal suckling (NS) group. Each group consisted of 24 cows with their calves (24 cows-calves/group = 24 cows and 24 calves/group). In the RS groups, suckling by the calves was restricted to once a day for 45 days, and then the calves were allowed to suckle normally throughout the remainder of the experiment. In the NS group, the calves suckled normally throughout the experiment. Experiment II compared 2 groups of RS cow-calves (24 cow-calves/group) with 2 groups of 24 NS cow-calves/group. In experiment I, there were no differences (P less than 0.05) in pregnancy rate or in the average number of nematode eggs/g of feces (epg) between the cows from the 2 treatment groups. The RS calves consistently had higher epg counts than did the NS calves during the 45 days of RS (169 vs 62 epg, P less than 0.05) and from the time of their return to pasture until weaning (266 vs 186 EPG, P = 0.27). The RS calves also had a higher average coccidia oocyst count during the RS period only. In experiment II, RS cows had a higher pregnancy rate (87.6% vs 66.0%, P less than 0.05) and a shorter postpartum interval (83 vs 101 days, P less than 0.05) than did NS cows.(ABSTRACT TRUNCATED AT 250 WORDS)

Efficacy of a large magnesium alloy rumen bolus in the prevention of hypomagnesemic tetany in cows

Two cow-calf grazing studies and 2 rate-of-disappearance trials in steers surgically prepared with rumen fistula were conducted to evaluate the efficacy of a large Mg alloy rumen bolus in preventing hypomagnesemic tetany (grass tetany). The mineral composition of the forage and results of study of 2 cows in the cow-calf studies indicated that an environment conducive to the occurrence of grass tetany existed. Grass tetany occurred in a cow that was given a Mg bolus and in a control cow. Administration of 1 or 2 mg boluses did not affect blood serum Mg, Ca, P, and K concentrations. Bolus treatment did not affect cow-calf performance or conception rate. The rate of weight loss of the boluses in the surgically prepared steers (rumen fistula) ranged from 0.71 to 1.43 g/day or 0.66 to 1.33 g of Mg/day. Steer differences affected the rates of disappearance patterns of the boluses. The rate of disappearance was relatively constant over a 175-day period and regurgitation or passage was not a problem. Although administration of the boluses could have prevented tetany in some animals (borderline), the rate of Mg release appears too slow to be highly effective in preventing grass tetany.

Effects of level of nitrogen fertilization of fescue pasture on gastrointestinal parasitism of beef cattle

Two established tall fescue pastures were used in a 4-year study of the relationship between the level of gastrointestinal parasitism in cattle and the level of nitrogen fertilization of the pasture. One pasture was fertilized with 224 kg of NH4NO3/ha each year and served as the control. A second pasture, referred to as the low-fertilized (LF) pasture, was fertilized with N at 84 kg/ha the first year and 74 kg/ha in each of the next 3 years. Both pastures were stocked with Angus cows (2.5/ha) and their calves. Rectal fecal samples obtained every 6 weeks from 10 cows and as many calves as possible in each pasture were examined for nemotode eggs and coccidia oocysts. Two calves from each group were slaughtered at the end of each of the last 3 years to determine the numbers and species of parasites. Cows had significantly lower egg counts than did the calves. Egg counts did not differ between the two groups of cows, but the control cows had higher average weights than the cows on the LF pasture. Control calves had significantly lower egg counts than the calves on the LF pasture, but only slightly higher mean adjusted 205-day weights. At necropsy, significantly fewer worms were recovered from the controls (17,977) than from the LF-pastured calves (52,332). Cooperia oncophora was the predominant species. The level of coccidia infection did not differ between the two groups of cows and calves. The greater availability of forage in the control than in the LF pasture probably was responsible for the lower level of parasitism in the control calves and for the greater weight gains made by the control cows and calves.