A preliminary survey of Chlamydia psittaci genotypes from native and introduced birds in New Zealand

AIM: To describe the Chlamydia psittaci genotypes in samples from native and introduced birds from New Zealand by analysis of the sequence variation of the ompA gene.

METHODS: DNA was extracted from samples collected from a non-random sample of birds; either swabs from live asymptomatic birds or birds with clinical signs, or formalin-fixed, paraffin-embedded (FFPE) samples from historical post-mortem cases. The presence of C. psittaci in all samples had been confirmed using a quantitative PCR assay. The C. psittaci ompA gene was amplified and sequenced from samples from 26 native and introduced infected birds comprising 12 different species. These sequences were compared to published available C. psittaci genotypes.

RESULTS: Genotypes A and C of C. psittaci were identified in the samples. Genotype A was identified in samples from nine birds, including various native and introduced species. Genotype C was identified in samples from 16 different waterfowl species, and a mixed infection of both genotypes was found in a kaka (Nestor meridionalis). In native birds, C. psittaci infection was confirmed in seven new host species.

CONCLUSIONS AND CLINICAL RELEVANCE: Two genotypes (A and C) of C. psittaci were found in samples from a wider range of both native and introduced species of birds in New Zealand than previously reported. Both genotypes have been globally associated with significant disease in birds and humans. These initial results suggest the host range of C. psittaci in New Zealand birds is under-reported. However, the prevalence of C. psittaci infection in New Zealand, and the associated impact on avian and public health, remains to be determined. There are biosecurity implications associated with the importation of birds to New Zealand if there is a limited diversity of C. psittaci genotypes present.     

High-resolution protein structure determination by serial femtosecond crystallography

Structure determination of proteins and other macromolecules has historically required the growth of high-quality crystals sufficiently large to diffract x-rays efficiently while withstanding radiation damage. We applied serial femtosecond crystallography (SFX) using an x-ray free-electron laser (XFEL) to obtain high-resolution structural information from microcrystals (less than 1 micrometer by 1 micrometer by 3 micrometers) of the well-characterized model protein lysozyme. The agreement with synchrotron data demonstrates the immediate relevance of SFX for analyzing the structure of the large group of difficult-to-crystallize molecules.     

Effects of protein phosphatase inhibitor calyculin a on the postacrosomal protein serine/threonine phosphorylation state and acrosome reaction in boar spermatozoa incubated with a cAMP analog

In order to reveal the involvement of the sperm postacrosomal region in the acrosome reaction, we examined the effects of the protein phosphatase inhibitor calyculin A on the postacrosomal protein serine/threonine phosphorylation state and acrosome morphology in boar spermatozoa incubated with a cAMP analog. Proteins were highly phosphorylated on the serine/threonine residues only in the postacrosomal region before incubation. After 90-min incubation without calyculin A, the protein phosphorylation state declined in the postacrosomal region irrespective of the capacitation state while it remained under the detectable level in the other regions of the sperm head. However, addition of calyculin A effectively suppressed the decline in protein phosphorylation state and increased an inactive form of protein phosphatase 1 in the postacrosomal region. On the other hand, this inhibitor had no influence on the protein phosphorylation state in the acrosome and equatorial segment. After incubation without calyculin A for 180 or 360 min, many spermatozoa exhibited acrosomal changes and loss that indicated occurrence of the acrosome reaction. However, addition of calyculin A significantly blocked these events. These results are consistent with our suggestion that postacrosomal serine/threonine-phosphorylated proteins are involved in suppression of the acrosome reaction in boar spermatozoa in vitro.     

Phytoplankton community structure and the drawdown of nutrients and CO2 in the southern ocean

Data from recent oceanographic cruises show that phytoplankton community structure in the Ross Sea is related to mixed layer depth. Diatoms dominate in highly stratified waters, whereas Phaeocystis antarctica assemblages dominate where waters are more deeply mixed. The drawdown of both carbon dioxide (CO2) and nitrate per mole of phosphate and the rate of new production by diatoms are much lower than that measured for P. antarctica. Consequently, the capacity of the biological community to draw down atmospheric CO2 and transport it to the deep ocean could diminish dramatically if predicted increases in upper ocean stratification due to climate warming should occur.     

The adenylate energy charge of the soil microbial biomass

A method was developed for measuring adenosine 5'-triphosphate (ATP), adenosine 5'-diphosphate (ADP) and adenosine 5'-monophosphate (AMP) in soil. All three adenine nucleotides were extracted from soil with a solution of trichloroacetic acid, paraquat and phosphate. ATP was measured in the neutralised (pH 7.4) soil extracts by the fire-fly luciferin-luciferase system. ADP was measured as ATP after incubating the neutralised extracts with pyruvate kinase (PK) and phosphoenolpyruvate (PEP) to convert ADP to ATP. AMP was converted to ATP by incubation with the coupled PK-PEP-myokinase system and measured as ATP. The quantities of nucleotides present in the extracts were corrected for incomplete extraction from soil by measuring the percentage recovery of added ATP, ADP and AMP. The adenylate energy charge (AEC) was calculated from the formula AEC = [[ATP] + 0.5[ADP]]/[[ATP] + [ADP] + [AMP]]. Measurements were made on (1) fresh soil, extracted as soon as possible after field sampling (2) soil stored air-dry at 5°C for 18 days and (3) soil stored air-dry at 5°C for 57 days and then rewetted to the original field moisture content and incubated aerobically for 2.5 h at 10°C before extraction.In moist soil the biomass maintains both ATP and AEC at levels close to those of activity growing cells, even though little of the biomass in soil can be in active growth at any given time. ATP accounted for 77% of the total adenine nucleotides (A_T) in the fresh soil, with an AEC of 0.85 (a value comparable to that found in microorganisms undergoing active growth in vitro. In contrast, ATP only accounted for 28% of A_T in the air-dried soil, with an AEC of 0.46. When the air-dried soil was rewetted, ATP increased to 66% of A_T and the AEC increased to 0.76. However, A_T in the air-dried soil (7.65 nmol g^?1 soil) was of the same order as that in rewetted soil (6.70 nmol g^?1) even though the AEC's were very different.These results show that the soil microbial biomass does not maintain a high AEC when air-dried. Once remoistened, the population tends to restore its AEC to the original value. This restoration occurs so rapidly that it cannot be due to the formation of a new biomass.     

Ostertagiasis in calves. I. The effect of control measures on infection levels and body weight gains during the grazing season in Denmark

The investigation was designed to study the gastro-intestinal helminth infection established in yearling calves with reference to fluctuations in the larval contamination of the herbage during the grazing season. In a 2 × 3 factor experiment, comprising six groups, each of six calves, a comparison was made between infection levels, growth rates etc. in calves grazing the same paddock over an entire season and calves moved before the July rise in herbage contamination to paddocks not grazed earlier in the same season. A comparison was also made between animals receiving no anthelminthic treatment, animals treated 3 weeks after the start of the grazing season and again when moved, and animals treated every 3 weeks during the season.Before July there were no weight gain differences between the various groups of calves. During the rest of the season, the calves which were moved gained 647–869 g, while those that remained on the same paddock, and were exposed to a high level of larval contamination gained only 81–361 g per day. The effect of anthelmintic treatment was less pronounced, though significant. The weight gains were correlated to a high degree with the larval contamination levels of the respective paddocks (r = ? 0.79) as well as with the serum pepsinogen (r = ? 0.75) and albumin levels (r = 0.75) of the calves and to a minor degree also with faecal egg counts (r = ? 0.45). The observed weight gain differences could not be accounted for by differences in grass quantity or quality.     

History, instrumentation, and techniques of flexible endoscopic laser surgery in horses.

There are clearly a number of applications for which flexible endoscopic laser surgery has become the state of the art in equine surgery, and the Nd:YAG laser seems to be the most versatile instrument for this type of surgery. Nevertheless, it is critical to understand the advantages and disadvantages of each laser technique. For example, the Nd:YAG laser used in a noncontact fashion seems to be superior when ablation of tissue is required such as treatment of upper airway masses. Conversely, contact Nd:YAG laser techniques have proven themselves to be superior when more precise cutting is advantageous such as treatment of epiglottic entrapment. Ultimately, it seems that a range of lasers is necessary to ensure selection of the most appropriate technique, adding significantly to the expense of equipment but improving the outcome for a range of equine diseases.     

Aspirin: intestinal damage in rats

Lesions induced by aspirin in the small intestine of the rat were visualized after 4 hours by the intravenous administration of a 5 percent solution of pontamine sky blue, 6 BX dye. Dose-response curves in fasted and fed rats indicated that the fed rat was about eight times more susceptible to aspirin-induced intestinal damage than was the fasted rat, while the fasted rat was about 13 times more susceptible to aspirin-induced gastric damage than was the fed rat.