Rates of evolution in ancient DNA from Adélie penguins

Well-preserved subfossil bones of Adélie penguins, Pygoscelis adeliae, underlie existing and abandoned nesting colonies in Antarctica. These bones, dating back to more than 7000 years before the present, harbor some of the best-preserved ancient DNA yet discovered. From 96 radiocarbon-aged bones, we report large numbers of mitochondrial haplotypes, some of which appear to be extinct, given the 380 living birds sampled. We demonstrate DNA sequence evolution through time and estimate the rate of evolution of the hypervariable region I using a Markov chain Monte Carlo integration and a least-squares regression analysis. Our calculated rates of evolution are approximately two to seven times higher than previous indirect phylogenetic estimates.

Nuclear DNA sequences detect species limits in ancient moa

Ancient DNA studies have typically used multi-copy mitochondrial DNA sequences. This is largely because single-locus nuclear genes have been difficult to recover from sub-fossil material, restricting the scope of ancient DNA research. Here, we have isolated single-locus nuclear DNA markers to assign the sex of 115 extinct moa and, in combination with a mitochondrial DNA phylogeny, tested competing hypotheses about the specific status of moa taxa. Moa were large ratite birds that showed extreme size variation both within and among species. For some taxa, this large variation was hypothesized to represent sexual dimorphism, while for others it was argued to reflect the existence of different species. Our results show that moa were characterized by extreme reverse sexual dimorphism and as a result we have been able to clarify the number of moa species. For example, we show that the three recognized 'species' of Dinornis comprised only two monophyletic groups and that two of these 'species' comprised individuals of one sex only. This study also illustrates that single-locus nuclear DNA sequences can be consistently recovered from ancient material.

ASW: a gene with conserved avian W-linkage and female specific expression in chick embryonic gonad

Vertebrates exhibit a variety of sex determining mechanisms which fall broadly into two classes: environmental or genetic. In birds and mammals sex is determined by a genetic mechanism. In mammals males are the heterogametic sex (XY) with the Y chromosome acting as a dominant determiner of sex due to the action of the testis-determining factor, SRY. In birds females are the heterogametic sex (ZW); however, it is not known whether the W chromosome carries a dominant ovary-determining gene, or whether Z chromosome dosage determines sex. Using an experimental approach, which assumes only that the sex-determining event in birds is accompanied by sex-specific changes in gene expression, we have identified a novel gene, ASW (Avian Sex-specific W-linked). The putative protein for ASW is related to the HIT (histidine triad) family of proteins. ASW shows female-specific expression in genital ridges and maps to the chicken W chromosome. In addition, we show that, with the exception of ratites, ASW is linked to the W chromosome in each of 17 bird species from nine different families of the class Aves.

Awake intubation increases intracranial pressure without affecting cerebral blood flow velocity in infants

Tracheal intubation is frequently required in neonatal anaesthetic practice. Awake intubation is one method of securing the airway and in certain circumstances, for many anaesthetists, can be preferable to intubation following induction of anaesthesia. Previous studies have inferred that the elevation in anterior fontanelle pressure observed during tracheal intubation in neonates was caused by an increase in cerebral blood flow although it was never measured. In this study, direct methods were used to observe changes in the cerebral circulation. Thirteen neonates, ASA I to III (E), aged from 1 to 34 days of age were studied. Patients were randomized to receive either tracheal intubation awake or following induction of anaesthesia with thiopentone 5 mg.kg-1 and succinylcholine 2 mg.kg-1. Heart rate, systolic arterial blood pressure, anterior fontanelle pressure, cerebral blood flow velocity (using transcranial Doppler sonography) and oxygen saturation were recorded at the following intervals: baseline (not crying), after intravenous atropine 0.02 mg.kg-1, during laryngoscopy, immediately after insertion of the endotracheal tube, one and five minutes later. The use of atropine masked the cardiovascular responses to intubation. Whereas the change in anterior fontanelle pressure from baseline was different between the groups (P < 0.05), the cerebral blood flow velocity variables were not. The rise in anterior fontanelle pressure seen in the awake group may be attributed to a reduction of the venous outflow from the cranium thereby increasing cerebral blood volume and subsequently the intracranial pressure.

Use of molecular assays in diagnosis and monitoring of cytomegalovirus disease following renal transplantation

We compared two commercial molecular assays (the Murex Hybrid Capture CMV DNA assay [HCA], version 2, and the Roche Amplicor plasma PCR assay) with a standard shell vial assay in detecting and predicting cytomegalovirus (CMV) disease in a group of renal transplant patients and assessed the role of viral load measurements (using the HCA) in their management. The sensitivity of the HCA and Amplicor assay in terms of disease detection was 100%, compared to 71% for the shell vial assay. Both the HCA and the PCR assay detected all cases of disease, at medians of 11 and 12.5 days before the onset of symptoms, respectively. Significantly higher viral loads were detected in those patients with symptoms (7.9 x 10(5) copies/ml) than in patients without symptoms (7.9 x 10(4) copies/ml; P < 0.0001). There was also a trend towards higher viral loads in those patients with primary infections (7.8 x 10(5) copies/ml) than in those patients with reactivations of CMV disease or reinfections. Successful treatment with ganciclovir was associated with a >90% reduction in viral load. Both of these new assays are sensitive and easy to use. A comparison of accurate quantitation is also useful in monitoring responses to antiviral therapy.

Single- and multilocus DNA fingerprinting of communally breeding pukeko: do copulations or dominance ensure reproductive success?

In behavioral and ecological studies the "function" of dominance hierarchies is thought to be related to reproductive success. In particular, dominant males are regarded as likely to gain a reproductive advantage due to enhanced "access" to females. We compare the dominance status of adults with the frequency of copulations and the patterns of parentage in communally breeding pukeko or purple swamphen (Porphyrio porphyrio melanotus). This avian species has an unusual social system, often breeding in polygynandrous groups in which there is a strong dominance hierarchy. Typically, during the breeding season, there is considerable sexual activity, with heterosexual and homosexual copulations between adults being commonplace. Hae III-digested DNA from individuals belonging to breeding groups was hybridized to the minisatellite DNA probe YNH24, revealing putative single-locus profiles, while hybridization of the same DNA to the minisatellite probes pV47-2, 3'HVR, and per revealed typical multilocus profiles. The numbers of unattributable restriction fragments allowed the maternity and paternity of all individuals to be conclusively determined, despite high levels of band sharing among individuals within breeding groups. These close genetic similarities are a likely consequence of strong philopatry and inbreeding. We report instances of males which are high on the dominance hierarchy but have only a limited reproductive output in comparison with others and males which are subordinate but achieve a significant proportion of fertilizations. Generally these data reveal no consistent relationship between dominance, the frequency of copulations, and parentage among males. We conclude that pukeko highlight some difficulties with conventional explanations for the "function" of dominance.

Microevolution and mega-icebergs in the Antarctic

Microevolution is regarded as changes in the frequencies of genes in populations over time. Ancient DNA technology now provides an opportunity to demonstrate evolution over a geological time frame and to possibly identify the causal factors in any such evolutionary event. Using nine nuclear microsatellite DNA loci, we genotyped an ancient population of Adélie penguins (Pygoscelis adeliae) aged approximately 6,000 years B.P. Subfossil bones from this population were excavated by using an accurate stratigraphic method that allowed the identification of individuals even within the same layer. We compared the allele frequencies in the ancient population with those recorded from the modern population at the same site in Antarctica. We report significant changes in the frequencies of alleles between these two time points, hence demonstrating microevolutionary change. This study demonstrates a nuclear gene-frequency change over such a geological time frame. We discuss the possible causes of such a change, including the role of mutation, genetic drift, and the effects of gene mixing among different penguin populations. The latter is likely to be precipitated by mega-icebergs that act to promote migration among penguin colonies that typically show strong natal return.

Is a large-scale DNA-based inventory of ancient life possible?

A complete DNA-based inventory of the Earth's present biota using large-scale high-throughput DNA sequencing of signature region(s) (DNA barcoding) is an ambitious proposal rivaling the Human Genome Project. We examine whether this approach will also enable us to assess the past diversity of the earth's biota. To test this, we sequenced the 5' terminus of the mitochondrial cytochrome c oxidase I (COI) gene of individuals belonging to a group of extinct ratite birds, the moa of New Zealand. Moa comprised a large number of taxa that radiated in isolation on this oceanic landmass. Using a phylogenetic approach based on a large data set including protein coding and 12S DNA sequences as well as morphology, we now have precise information about the number of moa species that once existed. We show that each of the moa species detected using this extensive data set has a unique COI barcode(s) and that they all show low levels of within-species COI variation. Consequently, we conclude that COI sequences accurately identify the species discovered using the larger data set. Hence, more generally, this study suggests that DNA barcoding might also help us detect other extinct animal species and that a large-scale inventory of ancient life is possible.

Cerebral arteriovenous malformations in children

The treatment of cerebral arteriovenous malformations (AVM) or vascular anomalies are challenging neurosurgical procedures for an anaesthetist. Large AVMs are uncommon in children. Only 18% of AVMs become symptomatic before the age of 15 yr. This series reviews the experience at this institution during the period of 1982 to 1992. The symptoms at the time of presentation are varied and include haemorrhage (50%), seizures and hydrocephalus (36%) or congestive cardiac failure (18%). Symptoms of congestive heart failure predominate in the newborn whilst neurological symptoms, such as stroke, seizures or hydrocephalus occur more commonly in infants and older children. Approximately one third of AVMs in childhood present acutely. Radiological investigations, e.g., CT scan, MRI and cerebral angiography are essential to identify the precise location of the lesion. Therapeutic intervention in the acute presentation may involve craniotomy for evacuation of haematoma and treatment of increased intracranial pressure (ICP). Control of seizures and congestive heart failure may take priority and allow time to plan the elective procedures of embolization and surgical excision of the AVM. Operative intervention is hazardous and peroperative complications can be expected in more than 50% of patients. The morbidity and mortality associated with cerebral AVM are high, especially in infants who present in the neonatal period with congestive cardiac failure. The overall mortality in this series was 20%. Children presenting with intracranial arteriovenous malformations require a multidisciplinary approach. The successful management of anaesthesia either for embolization or surgical resection necessitates an understanding of the disciplines of paediatric and neuroanaesthesia. Special care and specific attention to detail may contribute to reduce the high morbidity and mortality encountered in these compromised children.

Long term effects of gestational hypertension and pre-eclampsia on kidney function: Record linkage study

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We examine risk of chronic kidney disease (CKD) after pregnancy hypertension.

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We found increased risk of chronic kidney disease after gestational hypertension.

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Risk of chronic kidney disease was further increased after preeclampsia.

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Women with pregnancy hypertension develop CKD earlier than normotensive women.

Objective

To assess the long term effects of hypertensive disorders of pregnancy on renal function.

Design

Cohort study where exposure was gestational hypertension or preeclampsia in the first pregnancy. Normotensive women formed the comparison group.

Setting

Aberdeen, Scotland.

Participants

All women with date of birth on or before 30th June 1969 and at least their first singleton delivery recorded in the Aberdeen Maternity and Neonatal Databank.

Methods

Participants were linked to the Renal Biochemistry Register, Scottish Morbidity Records, Scottish Renal Registry and National Register for deaths.

Main outcome measures

Occurrence of chronic kidney disease (CKD) as identified from renal function tests in later life, hospital admissions or death from kidney disease or recorded as receiving renal replacement therapy.

Results

CKD was diagnosed in 7.5% and 5.2% of women who previously had GH and PE respectively compared to 3.9% in normotensive women. The unadjusted odds ratio (95% confidence interval) of having CKD in PE was 2.04 (1.53, 2.71) and that for GH was 1.37 (1.15, 1.65), while the adjusted odds ratio (95% confidence interval) of CKD was 1.93 (1.44, 2.57) and 1.36 (1.13, 1.63) in women with PE and GH respectively. Kaplan–Meier curves of survival time to development of chronic kidney disease revealed that women with preeclampsia were susceptible to kidney function impairment earliest, followed by those with gestational hypertension.

Conclusions

There was an increased subsequent risk of CKD associated with hypertensive disorders of pregnancy. Women with GH and PE were also found to have CKD earlier than normotensive women.

Perceptions of care and services by the clients and families: a personal experience

This study was initiated in response to a provincial mental health policy emphasizing the primacy of the person and the hospital's decision to adopt total quality management. The objective of the project was to learn more about how clients and families viewed the care and services received during a psychiatric admission. Their perceptions were elicited through seven focus groups including multiple admission (3) clients and families of single and multiple admission clients (2 each). Group sessions were tape-recorded, transcribed and analysed for themes. Three major themes were identified: quantity and quality of care, individuality and partnership. Both positive and negative comments were made within each of these themes, but two major areas for improvement were continuity of care and the environment. The findings are being used to change practices within the Department of Psychiatry.

The bovine arterially-perfused eye: an in vitro method for the study of drug mechanisms on IOP, aqueous humour formation and uveal vasculature

A method is reported in which the isolated bovine eye is perfused through a long posterior ciliary artery with buffered physiological saline, to provide simultaneous monitoring of drug effects on intraocular pressure (IOP), vascular resistance and the condition of the blood-aqueous barrier. With perfusion under constant pressure of 45 mm Hg, perfusate flows at 1.64 +/- 0.12 ml.min-1 (mean +/- SEM) and IOP is 7.26 +/- 0.16 mm Hg. Applying a constant flow rate of 2.25 ml.min-1, IOP averages 10.19 +/- 0.32 mm Hg and in both cases this can be maintained for around 2h. Increasing the perfusion flow rate from 1.5 to 3.5 ml.min-1 produces a 76% rise in perfusion pressure but IOP increases only insignificantly (< 10%). The inclusion in the perfusion fluid of dextran and albumin to maintain oncotic pressure similar to that of plasma makes no difference to the IOP achieved and does not affect the leakiness of the barrier. The preparation shows a net consumption of oxygen, supporting the hypothesis that the aqueous humour formed is secreted by active transport processes. Timolol (in bolus doses of 1-300 nmol) injected into the perfusing fluid is shown to induce a dose-dependent fall in IOP within 5 min, reaching a steady state within 40 min. Timolol, however, causes no significant change in vascular resistance, whether this is measured as perfusion flow rate under constant pressure or as perfusion pressure at constant flow rate, nor does it alter the permeability of the barrier. Other beta-blockers such as oxprenolol and betaxolol also induce dose-dependent decreases in IOP. By applying a fluorescein dilution technique, it is found that the aqueous formation rate (K(out) = 0.0046 min-1, or 12.9 microliters.min-1) is also reduced by timolol and, in a dose-dependent manner, by the new carbonic anhydrase inhibitor, MK-927. The bovine perfused eye offers a useful method for studying the mechanisms of action of drugs on IOP and aqueous humour formation, in isolation from the complicating influences of the CNS and the cardiovascular system and without the necessity to kill animals for experimental purposes.

Low body mass not vitamin D receptor polymorphisms predict osteoporosis in patients with inflammatory bowel disease

BACKGROUND

Osteoporosis is a recognized complication of inflammatory bowel disease (IBD). Aim To investigate the role of environmental factors and vitamin D receptor (VDR) variants on the prevalence of osteoporosis.

METHODS

DEXA scans and case note review were performed on 440 IBD patients from 1997 to 2006. All the IBD patients and 240 healthy controls were genotyped for VDR variants Taq-1 and Apa-1 using PCR-RFLP.

RESULTS

Osteoporosis and osteopenia rates were 15% and 18% for IBD, 16% and 18% for Crohn's disease (CD) and 13% and 19% for ulcerative colitis, respectively. On univariate analysis of the CD patients, low body mass index (BMI, <18.5) and smoking status (P = 0.008 and 0.005 respectively) were associated with osteoporosis and osteopenia. Low BMI was also associated with osteoporosis on multivariate analysis in CD (P = 0.021, OR 5.83, CI 1.31-25.94). No difference was observed between Taq-1 and Apa-1 VDR polymorphisms in IBD, CD, ulcerative colitis and healthy controls. However, CD males were more likely to carry the variant Taq-1 polymorphism than healthy controls males (P = 0.0018, OR 1.94, CI 1.28-2.92) and female CD patients (P = 0.0061, OR 1.60, CI 1.17-2.44).

CONCLUSIONS

In this well-phenotyped cohort of IBD patients, a relatively low prevalence of osteoporosis was observed. Low BMI was the only independent risk factor identified to be associated with osteoporosis.

Ancient DNA recovers the origins of Māori feather cloaks

Feather cloaks ("kakahu"), particularly those adorned with kiwi feathers, are treasured items or "taonga" to the Māori people of "Aotearoa"/New Zealand. They are considered iconic expression of Māori culture. Despite their status, much of our knowledge of the materials used to construct cloaks, the provenance of cloaks, and the origins of cloak making itself, has been lost. We used ancient DNA methods to recover mitochondrial DNA sequences from 849 feather samples taken from 109 cloaks. We show that almost all (>99%) of the cloaks were constructed using feathers from North Island brown kiwi. Molecular sexing of nuclear DNA recovered from 92 feather cloak samples also revealed that the sex ratio of birds deviated from a ratio of 1:1 observed in reference populations. Additionally, we constructed a database of 185 mitochondrial control region DNA sequences of kiwi feathers comprising samples collected from 26 North Island locations together with data available from the literature. Genetic subdivision (G(ST)), nucleotide subdivision (N(ST)) and Spatial Analysis of Molecular Variants (SAMOVA) analyses revealed high levels of genetic structuring in North Island brown kiwi. Together with sequence data from previously studied ancient and modern kiwi samples, we were able to determine the geographic provenance of 847 cloak feathers from 108 cloaks. A surprising proportion (15%) of cloaks were found to contain feathers from different geographic locations, providing evidence of kiwi trading among Māori tribes or organized hunting trips into other tribal areas. Our data also suggest that the east of the North Island of New Zealand was the most prolific of all kiwi cloak making areas, with over 50% of all cloaks analyzed originating from this region. Similar molecular approaches have the potential to discover a wealth of lost information from artifacts of endemic cultures worldwide.

Effects of H-7 on the iris and ciliary muscle in monkeys

OBJECTIVES

To determine the effects of H-7 on (1) iris and ciliary muscles (CMs) in living monkeys; (2) isolated monkey CM strips; (3) actomyosin contractility in cultured Swiss 3T3 cells.

METHODS

(1) Pupillary diameter (calipers) and accommodation (refractometer) in living monkeys were measured after topical, intracameral, or intravitreal administration of H-7 followed by systemic pilocarpine hydrochloride. (2) Pilocarpine-induced contraction of isolated monkey CM strips following administration of H-7 was measured in a perfusion chamber. (3) Actomyosin contractility in Swiss 3T3 cells cultured on thin silicone rubber film was determined by measuring cell-induced film wrinkles before and after administration of H-7.

RESULTS

Topical H-7 prevented anesthesia-induced miosis but did not affect resting refraction. Intracameral or intravitreal H-7 dilated the pupil and inhibited miotic but not accommodative responses to pilocarpine. H-7 inhibited pilocarpine-induced contraction of isolated monkey CM strips and reduced Swiss 3T3 cell contraction.

CONCLUSIONS

H-7 inhibits actin-based contractility in non-muscle cells and in monkey iris sphincter and CM. Under our in vivo experimental conditions, the effect on the iris predominates over that on the CM.

Ancient population genomics and the study of evolution

Recently, the study of ancient DNA (aDNA) has been greatly enhanced by the development of second-generation DNA sequencing technologies and targeted enrichment strategies. These developments have allowed the recovery of several complete ancient genomes, a result that would have been considered virtually impossible only a decade ago. Prior to these developments, aDNA research was largely focused on the recovery of short DNA sequences and their use in the study of phylogenetic relationships, molecular rates, species identification and population structure. However, it is now possible to sequence a large number of modern and ancient complete genomes from a single species and thereby study the genomic patterns of evolutionary change over time. Such a study would herald the beginnings of ancient population genomics and its use in the study of evolution. Species that are amenable to such large-scale studies warrant increased research effort. We report here progress on a population genomic study of the Adélie penguin (Pygoscelis adeliae). This species is ideally suited to ancient population genomic research because both modern and ancient samples are abundant in the permafrost conditions of Antarctica. This species will enable us to directly address many of the fundamental questions in ecology and evolution.

Bladder epithelial oxygen tension--a new means of monitoring regional perfusion? Preliminary study in a model of exsanguination/fluid repletion

OBJECTIVE

To assess whether monitoring of bladder epithelial oxygen tension (BEOT) would provide an indication of regional (renal) organ perfusion in an exsanguination/fluid repletion animal model.

DESIGN

Prospective non-randomized laboratory study.

SETTING

Research laboratory.

INTERVENTIONS

Eight anaesthetised, spontaneously breathing Sprague-Dawley male rats weighing approximately 200 g were instrumented. They received 1-ml aliquots of fluid until no further haemodynamic improvement was seen, followed by removal of 1-ml aliquots of blood until renal blood flow fell by 50%. The animal was then resuscitated with repeated 1 to 2-ml aliquots of fluid until no further improvement was achieved and, finally, progressively exsanguinated to cardiovascular collapse.

MEASUREMENTS AND RESULTS

A continuous Clark-type oxygen electrode lying in contact with the inside wall of the bladder measured changes in BEOT during these exsanguination and fluid repletion manoeuvres. Changes in BEOT closely mirrored both systemic (blood pressure and aortic blood flow) and regional (renal blood flow) haemodynamic changes. A direct correlation existed between percentage change in BEOT and base deficit, and an indirect correlation was seen with arterial oxygen tension.

CONCLUSIONS

Measurement of BEOT may be a useful and relatively non-invasive means of monitoring regional organ perfusion. Further studies are warranted.

Refractory cachexia and truth-telling about terminal prognosis: a qualitative study

The purpose of this paper is to examine the consequences that medical practitioners' decisions about whether or not to be candid about terminal prognosis have for those suffering from refractory cachexia and their families. It presents the findings of a qualitative study that used focus groups and semi-structured interviews of a volunteer sample of doctors, nurses and dieticians in a cancer centre of a large teaching hospital in Northern Ireland. Respondents reported that some physicians tended to avoid discussing terminal prognosis in a direct manner with their patients. Nurses and dieticians tended to be reluctant to engage in conversations about weight loss with patients with cachexia. One of the reasons they reported for their lack of acknowledgement of weight loss concerned the close association between refractory cachexia and terminal prognosis. Because they viewed the telling of bad news as an exclusive prerogative of medical practitioners, they did not feel in a position to discuss cachexia because they were concerned that this had the potential to raise end-of-life issues that lay outside the boundaries of their professional role. This meant patients and their families were provided with little information about how to cope with the distressing consequences of cachexia.

PVDF reference hydrophone development in the UK-from fabrication and lamination to use as secondary standards

During the last 30 yrs, PVDF has been used extensively as a sensor material. Over this period, the GEC-Marconi Research Centre has developed a wide range of devices based on PVDF as a piezoelectric transducer material. The ability to create laminated structures has led to an enhancement in performance and has allowed innovative designs to be realized. This paper describes the development of the laminated PVDF structure and its benefits, such as increased sensitivity and improved signal to noise ratio. Examples of devices utilizing the lamination process are given in the form of both a bilaminar-shielded membrane hydrophone and a PVDF sonar hydrophone. Performance properties of both types of hydrophones are presented along with a discussion of their use as secondary standard hydrophones at the National Physical Laboratory (NPL).

Effects of timolol, terbutaline and forskolin on IOP, aqueous humour formation and ciliary cyclic AMP levels in the bovine eye

We have studied the effects of terbutaline, timolol, forskolin and 8-bromo cyclic AMP on aqueous humour formation, intraocular pressure and on ciliary epithelial cyclic AMP levels, either in presence or in absence of IBMX, using the bovine isolated arterially perfused eye, excised ciliary processes and cultured ciliary epithelium. Both terbutaline, a beta-adrenoceptor agonist, and timolol, a beta-adrenoceptor antagonist, caused significant reduction in aqueous humour formation and intraocular pressure but produced no effect on ciliary epithelial cyclic AMP content in the absence of IBMX. Even a three times higher dose of terbutaline was entirely ineffective in producing any effect on ciliary cyclic AMP in the perfused eye. On the other hand, terbutaline at the IOP-reducing dose, produced a significant increase in cyclic AMP when injected after 30 min perfusion with IBMX. Incubation of excised ciliary processes or cultured ciliary epithelial cells with terbutaline (10(-6) to 10(-4) M) produced concentration-dependent increases in cyclic AMP, in both tissues, even in the absence of IBMX. Forskolin, which stimulates cyclic AMP synthesis without interacting with cell surface receptors, was found to produce highly significant increases in ciliary cyclic AMP content both in presence and in absence of IBMX but had no effect on aqueous humour formation in the isolated eye. IBMX perfused at concentrations of 1 mM or 10 microM had no effect on basal levels of ciliary cyclic AMP but the 1 mM concentration produced a marked and significant reduction in IOP. Direct application of 8-bromo cyclic AMP, a cell permeable analogue, more resistant to hydrolysis by phosphodiesterases, had also no effect on aqueous humour formation in the perfused eye. It is concluded that in the bovine arterially perfused eye, the correlation between the aqueous humour formation rate and ciliary epithelial cyclic AMP content is unclear.

Molecular sexing of the communally breeding pukeko: an important ecological tool

A central biological parameter in the study of any animal population is the accurate assignment of sex. Indeed any ecological study of a population requires information on sex composition in relation to such biological factors as behaviour, movement, mortality and birth rate. However, our ability to assign the sex of adults of many avian species is poor and the sexing of young is universally difficult. We report here the successful application of a molecular technique for the assignment of sex in the communally breeding pukeko or purple swamphen (Porphyrio porphyrio melanotus). W- and Z-linked chromosome fragments in digested genomic DNA of pukeko were detected with the DNA probe pMg1. We consequently show that this species breeds in polyandrous, polygynous and polygynandrous groups. Finally we discuss why recent molecular methods represent important new tools in ecology.

Bucking the trend: genetic analysis reveals high diversity, large population size and low differentiation in a deep ocean cetacean

Understanding the genetic structure of a population is essential to its conservation and management. We report the level of genetic diversity and determine the population structure of a cryptic deep ocean cetacean, the Gray's beaked whale (Mesoplodon grayi). We analysed 530 bp of mitochondrial control region and 12 microsatellite loci from 94 individuals stranded around New Zealand and Australia. The samples cover a large area of the species distribution (~6000 km) and were collected over a 22-year period. We show high genetic diversity (h=0.933-0.987, π=0.763-0.996% and Rs=4.22-4.37, He=0.624-0.675), and, in contrast to other cetaceans, we found a complete lack of genetic structure in both maternally and biparentally inherited markers. The oceanic habitats around New Zealand are diverse with extremely deep waters, seamounts and submarine canyons that are suitable for Gray's beaked whales and their prey. We propose that the abundance of this rich habitat has promoted genetic homogeneity in this species. Furthermore, it has been suggested that the lack of beaked whale sightings is the result of their low abundance, but this is in contrast to our estimates of female effective population size based on mitochondrial data. In conclusion, the high diversity and lack of genetic structure can be explained by a historically large population size, in combination with no known exploitation, few apparent behavioural barriers and abundant habitat.