Ribozyme-catalyzed transcription of an active ribozyme

A critical event in the origin of life is thought to have been the emergence of an RNA molecule capable of replicating a primordial RNA "genome." Here we describe the evolution and engineering of an RNA polymerase ribozyme capable of synthesizing RNAs of up to 95 nucleotides in length. To overcome its sequence dependence, we recombined traits evolved separately in different ribozyme lineages. This yielded a more general polymerase ribozyme that was able to synthesize a wider spectrum of RNA sequences, as we demonstrate by the accurate synthesis of an enzymatically active RNA, a hammerhead endonuclease ribozyme. This recapitulates a central aspect of an RNA-based genetic system: the RNA-catalyzed synthesis of an active ribozyme from an RNA template.     

Modeling effects of environmental change on wolf population dynamics, trait evolution, and life history

Environmental change has been observed to generate simultaneous responses in population dynamics, life history, gene frequencies, and morphology in a number of species. But how common are such eco-evolutionary responses to environmental change likely to be? Are they inevitable, or do they require a specific type of change? Can we accurately predict eco-evolutionary responses? We address these questions using theory and data from the study of Yellowstone wolves. We show that environmental change is expected to generate eco-evolutionary change, that changes in the average environment will affect wolves to a greater extent than changes in how variable it is, and that accurate prediction of the consequences of environmental change will probably prove elusive.     

Quantification of tissue uric acid levels in a Harris's hawk with visceral gout

A young, captive-bred Harris's hawk, Parabuteo unicinctus, exhibited high fever and apparent paralysis of one leg shortly before death. Postmortem examination revealed milky white kidneys, white crystalline deposits in the pericardial sack, and white crystals in one intertarsal joint. Uric acid concentrations determined for the kidneys, heart muscle, skeletal muscle, and scrapings from the pericardial sack (20 mg) and intertarsal joint (2 mg) were, respectively, 12,200, 200, 110, 20,700, and 43,000 mg/100 g tissue. Compared with a healthy hawk, concentrations were elevated by a factor of 50 in the kidneys, 37 in skeletal muscle, and 18 in cardiac muscle.     

Occurrence and distribution of earthworms in agricultural landscapes across Europe with regard to testing for responses to plant protection products

Purpose

Within the regulatory framework for authorisation of plant protection products (PPPs) (EU Directive 91/414/1991/EEC replaced by Regulation (EC) 1107/2009), higher tier risk assessments and earthworm field tests are conducted in different countries across Europe. This paper describes dominant earthworm species for regulatory and biogeographical regions in agricultural landscapes across Europe and examines regional differences in earthworm communities and densities and their respective response to a toxic reference.

Materials and methods

For the assessment of earthworm abundance and species distribution, data of untreated control plots from 30 earthworm field studies were analysed; each conducted according to the ISO 11268–3 (1999) guideline by European Crop Protection Association member companies in the context of registration of PPPs. For the evaluation of the response to PPPs under different regional and climatic conditions, the effect on earthworm abundance was assessed by comparing plots treated with toxic references with untreated control plots. Additionally, a comparative literature review was included providing an overview of earthworm species composition and densities in agricultural crops from 14 European countries.

Results and discussion

The assessment of earthworm field studies from six different European countries revealed that common earthworm species of anecic and endogeic ecological groups are present at most field sites. Dominant species groups of endogeic and anecic earthworms can be defined that are abundant in all assessed countries. These are the endogeic species Aporrectodea caliginosa, Aporrectodea rosea and Allolobophora chlorotica, and the anecic species Lumbricus terrestris (Northern and Central Europe) and Lumbricus friendi (Southern Europe). Taking into account the high variability in total earthworm abundances, it can be concluded that the variability within regions was larger than the variability between regions.

Conclusions

Analysis of the earthworm community and data of toxic references lead to the conclusion that testing in different zones is not considered necessary.     

The possible adaptive advantages of terrestrial egg deposition in some fluvial diadromous galaxiid fishes (Teleostei: Galaxiidae)

Several diadromous New Zealand and Australian species of Galaxias are now known, or suspected, to deposit their eggs amongst riparian vegetation or substrates either supratidally in estuaries or in forested streams in locations that are only temporarily submerged by elevated water levels. The eggs develop in a humid atmosphere and hatch when the egg deposition sites are resubmerged; a significant role for agitation in stimulating hatching seeming likely. There are risks from the eggs becoming dehydrated, and also from a failure by water to resubmerge the eggs before they have exhausted their energy resources. Hatching is triggered by elevated flows, perhaps being an outcome of agitation of the eggs. Elevated flows may also increase the rate of downstream transport of the larvae, facilitating survival during dispersal to sea from spawning sites in streams that may be long distances inland. Hatching during flood events may favour survival of the larvae because turbid flows may provide ‘cover’ for the larvae as they emigrate to sea. Risks from egg predation by aquatic predators may be replaced by risks from terrestrial predators.     

Study of Sperm Concentration,Seminal Plasma Composition and their Physiological Correlation in the Persian Sturgeon,Acipenser persicus

The objectives of the present study were to determine ionic and organic composition of seminal plasma, sperm concentration and their relationships in the Persian sturgeon (Acipenser persicus). In this regard, ionic content (Na⁺, K⁺, Cl^?, Ca²⁺ and Mg²⁺) and organic content (total protein, glucose, cholesterol and triglyceride) along with sperm concentration were measured in 17 specimens of the Persian sturgeon. The seminal plasma contained 59.53 ± 2.56 mm /l sodium, 9.1 ± 1.42 mm chloride, 4.72 ± 0.3 mm potassium, 1.45 ± 0.075 mm calcium and 0.7 ± 0.072 mm magnesium. The following organic contents were found: total protein 0.11 ± 0.02 g/dl, glucose 22.18 ± 4.16 mg/dl, cholesterol 6.67 ± 1.04 mg/dl and triglyceride 15.2 ± 0.65 mg/dl. The mean sperm concentration was estimated to be 1.6 ± 0.12 (×10⁹ sperm/ml). A significant relationship was found between sperm concentration and K⁺ of seminal plasma (r = 0.533, p < 0.05). Significant correlations were observed between ionic contents: Na⁺ vs Cl^? (r = ?0.854, p < 0.01) and Mg²⁺ vs K⁺ (?0.583, p < 0.05). Also, level of triglyceride was negatively correlated with Mg²⁺ (r = ?0.503, p < 0.05). Presented data could be considered as a complementary study for developing special extenders and protectant solutions for improving artificial fertilization in this valuable species.     

Distribution of prion protein genotypes in breeds of sheep in New Zealand

AIM: To use an established high through-put genotyping procedure to gain an estimate of the frequency of alleles of the prion protein (PrP) gene in some common sheep breeds in New Zealand.

METHODS: Using a genotyping procedure based on matrix-assisted laser desorption ionisation-time of flight (MALDI-TOF), DNA samples from 3,024 sheep from New Zealand, including breeds such as Romney, Texel, Coopworth, Merino and mixedbreed, were isolated, genotyped and the results analysed.

RESULTS: The 15 scrapie genotypes commonly reported, and derived from the five commonly reported allelic variants (ARR, ARQ, AHQ, ARH and VRQ), were all observed in the samples analysed. The estimates were indicative of the frequencies in the population of alleles present in breeds of sheep in New Zealand. There was a significant difference between the frequencies of alleles between breeds, but the ARQ, followed by the ARR allele, were, except in Carwell sheep, the most common alleles present.

CONCLUSION: This study gave an indication of the percentages of PrP gene alleles in sheep in New Zealand, including data previously unreported from breeds in this country. It is of interest because of the relatively large size of the sheep population in New Zealand compared with many countries, and it provides some useful information on the genetic susceptibility or resistance of the sheep population in New Zealand to scrapie. The frequencies of the alleles can be different for an individual breed compared between countries.     

Distal aortic aneurysm presumed to be secondary to an infected umbilical artery in a foal

Abstract

CASE HISTORY:?A 3-month-old female Warmblood foal was presented after displaying signs of colic with pyrexia for 5 days.

CLINICAL AND PATHOLOGICAL FINDINGS:?The foal continued to show signs of colic, frequently passed urine, and was pyrexic with an elevated white blood cell count. The umbilical stalk was thickened but there was no evidence of purulent material. Exploratory laparotomy revealed an enlarged left umbilical artery remnant tightly adhered to the bladder wall. The left umbilical artery continued to an aneurysm involving the distal aorta. The foal was subject to euthanasia and post-mortem examination confirmed a spherical aortic aneurysm, in the dorsal midline caudal to the kidneys that contained a large thrombus. Histopathological examination revealed inflammation and necrosis of the tunica intima and tunica media of the left umbilical artery with suppuration and bacterial colonies evident in the periarterial tissues.

DIAGNOSIS:?Infected aortic aneurysm presumably caused by an umbilical artery infection.

CLINICAL RELEVANCE:?A previously undetected umbilical infection appears to have resulted in an unusual delayed complication causing signs of colic in a foal. Veterinarians should be aware of this condition, and the possibility that it may be a cause of signs of colic in foals. Diagnosis based on ultrasonography should be possible, but may require sedation, visceral analgesia and careful examination.     

Pulsed-field gel electrophoresis typing of Campylobacter fetus subsp. fetus isolated from sheep abortions in New Zealand

AIMS: To genotype Campylobacter fetus subsp. fetus isolates cultured from sheep abortions submitted to diagnostic laboratories in New Zealand during the year 2000 breeding season. To compare the types found nationally with those found in the Hawke' Bay region in 1999, and strains held in the New Zealand Reference Culture Collection, Medical Section (NZRM) from a study published in 1987.

METHODS: Campylobacter fetus subsp. fetus isolates cultured by veterinary diagnostic laboratories in the year 2000 breeding season, from sheep abortions from throughout New Zealand, were typed using pulsed-field gel electrophoresis (PFGE). In addition, seven freeze-dried C. fetus subsp. fetus isolates (strain numbers 2939–2945) from the NZRM, representing restriction types a–g found amongst sheep abortion isolates in a study published in 1987, were typed using PFGE.

RESULTS: In total, 293 C. fetus subsp. fetus isolates from 200 farms were obtained from veterinary diagnostic laboratories. Twenty-two distinct PFGE profiles were identified amongst the isolates. PFGE type B1 was predominant in each region of New Zealand and was identified from 66% of farms overall. Of the C. fetus subsp. fetus restriction types a–g lodged with the NZRM, 3/7 had PFGE profiles indistinguishable from profiles found in the current study. The other four restriction types had PFGE profiles that were unique but similar to those found in the current study.

CONCLUSIONS: PFGE type B1 was predominant amongst the C. fetus subsp. fetus isolates cultured from sheep abortions in each region of New Zealand in the year 2000, as was found in Hawke' Bay in 1999. The similarity between PFGE profiles of C. fetus subsp. fetus sheep abortion isolates from 1987 and 2000, and the relative prevalence of the PFGE groups, suggests that there has been no major genotypic shift in the population of C. fetus subsp. fetus implicated in sheep abortion in New Zealand during this time.