Reproduction in the squirrel glider, Petaurus norfolcensis (Petauridae) in south-east Queensland

Reproduction was studied across a three-year period in two south-east Queensland populations of the squirrel glider, Petaurus norfolcensis, by measuring morphological (body weight, scrotal diameter, cutaneous scent-gland activity, condition index) and physiological (plasma steroid levels) variables. Reproduction showed a seasonal pattern, with peak numbers of pouch young recorded in late autumn and winter. Declines in oestrogen concentrations outside the breeding period indicate that females are anoestrous in the summer months. Most (83%) reproductive females captured during the study were 2-3 years old, but all individuals over one year of age were found to have bred. Average litter size was 1.73 +/- 0.01 (n = 23). Scrotal diameter and testosterone concentrations showed no significant seasonal variation. It is suggested that this is due to the presence of both socially dominant and subordinate males in the data set. Maximum testosterone concentrations did coincide with periods of mating. The condition index showed no relationship with reproductive variables, but it is likely that this results from the manner in which the index was generated.

Breeding for low input conditions and consequences for participatory plant breeding: Examples from tropical maize and wheat

Participatory plant breeding (PPB) has been suggested as an effective alternative to formal plant breeding (FPB) as a breeding strategy for achieving productivity gains under low input conditions. With genetic progress through PPB and FPB being determined by the same genetic variables, the likelihood of success of PPB approaches applied in low input target conditions was analyzed using two case studies from FPB that have resulted in significant productivity gains under low input conditions: (1) breeding tropical maize for low input conditions by CIMMYT, and (2) breeding of spring wheat for the highly variable low input rainfed farming systems in Australia. In both cases, genetic improvement was an outcome of long-term investment in a sustained research effort aimed at understanding the detail of the important environmental constraints to productivity and the plant requirements for improved adaptation to the identified constraints, followed up by the design and continued evaluation of efficient breeding strategies. The breeding strategies used differed between the two case studies but were consistent in their attention to the key determinants of response to selection: (1) ensuring adequate sources of genetic variation and high selection pressures for the important traits at all stages of the breeding program, (2) use of experimental procedures to achieve high levels of heritability in the breeding trials, and (3) testing strategies that achieved a high genetic correlation between performance of germplasm in the breeding trials and under on-farm conditions. The implications of the outcomes from these FPB case studies for realizing the positive motivations for adopting PPB strategies are discussed with particular reference for low input target environment conditions.

The use of perineal ultrasound to quantify levator activity and teach pelvic floor muscle exercises

Perineal ultrasound was used to detect and quantify levator activity by measuring the displacement of the internal urethral meatus against the inferoposterior margin of the symphysis pubis, Women who had previously been instructed in pelvic floor muscle exercises were more likely to contract the levator muscle when asked to do so than were those without previous instruction (P

Activity of recombinant dengue 2 virus NS3 protease in the presence of a truncated NS2B co-factor, small peptide substrates, and inhibitors

Recombinant forms of the dengue 2 virus NS3 protease linked to a 40-residue co-factor, corresponding to part of NS2B, have been expressed in Escherichia coli and shown to be active against para-nitroanilide substrates comprising the P6-P1 residues of four substrate cleavage sequences. The enzyme is inactive alone or after the addition of a putative 13-residue co-factor peptide but is active when fused to the 40-residue co-factor, by either a cleavable or a noncleavable glycine linker. The NS4B/NS5 cleavage site was processed most readily, with optimal processing conditions being pH 9, I = 10 mm, 1 mm CHAPS, 20% glycerol. A longer 10-residue peptide corresponding to the NS2B/NS3 cleavage site (P6-P4') was a poorer substrate than the hexapeptide (P6-P1) para-nitroanilide substrate under these conditions, suggesting that the prime side substrate residues did not contribute significantly to protease binding. We also report the first inhibitors of a co-factor-complexed, catalytically active flavivirus NS3 protease. Aprotinin was the only standard serine protease inhibitor to be active, whereas a number of peptide substrate analogues were found to be competitive inhibitors at micromolar concentrations.

Brain activity during the encoding, retention, and retrieval of stimulus representations

Studies of delayed nonmatching-to-sample (DNMS) performance following lesions of the monkey cortex have revealed a critical circuit of brain regions involved in forming memories and retaining and retrieving stimulus representations. Using event-related functional magnetic resonance imaging (fMRI), we measured brain activity in 10 healthy human participants during performance of a trial-unique visual DNMS task using novel barcode stimuli. The event-related design enabled the identification of activity during the different phases of the task (encoding, retention, and retrieval). Several brain regions identified by monkey studies as being important for successful DNMS performance showed selective activity during the different phases, including the mediodorsal thalamic nucleus (encoding), ventrolateral prefrontal cortex (retention), and perirhinal cortex (retrieval). Regions showing sustained activity within trials included the ventromedial and dorsal prefrontal cortices and occipital cortex. The present study shows the utility of investigating performance on tasks derived from animal models to assist in the identification of brain regions involved in human recognition memory.

Determination of breeding strategies for beef cattle bull breeders selling bulls into two competing markets on a non-linear price grid

Computer simulation was used to suggest potential selection strategies for beef cattle breeders with different mixes of clients between two potential markets. The traditional market paid on the basis of carcass weight (CWT), while a new market considered marbling grade in addition to CWT as a basis for payment. Both markets instituted discounts for CWT in excess of 340 kg and light carcasses below 300 kg. Herds were simulated for each price category on the carcass weight grid for the new market. This enabled the establishment of phenotypic relationships among the traits examined [CWT, percent intramuscular fat (IMF), carcass value in the traditional market, carcass value in the new market, and the expected proportion of progeny in elite price cells in the new market pricing grid]. The appropriateness of breeding goals was assessed on the basis of client satisfaction. Satisfaction was determined by the equitable distribution of available stock between markets combined with the assessment of the utility of the animal within the market to which it was assigned. The best goal for breeders with predominantly traditional clients was a CWT in excess of 330 kg, while that for breeders with predominantly new market clients was a CWT of between 310 and 329 kg and with a marbling grade of AAA in the Ontario carcass pricing system. For breeders who wished to satisfy both new and traditional clients, the optimal CWT was 310-329 kg and the optimal marbling grade was AA-AAA. This combination resulted in satisfaction levels of greater than 75% among clients, regardless of the distribution of the clients between the traditional and new marketplaces.

Changes in progesterone and testosterone during the breeding season of the large-footed myotis Myotis moluccarum (Microchiroptera : Vespertilionidae)

The reproductive biology of the large-footed myotis, Myotis moluccarum, was studied during the annual breeding season in southeast Queensland, Australia. Previous research has shown the species to be polyoestrous and monotoccous, producing two consecutive young with some degree of synchrony in late October to early November and again in late January to early February. Hormonal data was collected and observations of the female reproductive tract made in order to ascertain the reproductive cycle of this species. In July, when females were not pregnant, progesterone concentrations were 1.9 +/- 0.9 ng/ml. During the two gestation periods, progesterone concentrations increased progressively until late pregnancy at the end of October through to early November and again in late January to early February. During the latest stages of pregnancy, progesterone concentrations of 69.9 +/- 18.7 ng/ml were reached. It is suggested that a plasma progesterone concentration in excess of about 8 ng/ml indicates pregnancy in this species. Plasma testosterone concentration in males reached a peak of 43.1 +/- 9.81 ng/ml in July, and was then variable until December when levels declined significantly to 2.0 +/- 1.7 ng/ml.

Energy cost of physical activity in cystic fibrosis

Objective: The purpose of this study was to compare the energy cost of standardized physical activity (ECA) between patients with cystic fibrosis (CF) and healthy control subjects. Design: Cross-sectional study using patients with CF and volunteers from the community. Setting: University laboratory. Subjects: Fifteen patients (age 24.6 +/- 4.6 y) recruited with consent from their treating physician and 16 healthy control subjects (age 25.3 +/- 3.2) recruited via local advertisement. Interventions. Patients and controls walked on a computerised treadmill at 1.5 km/h for 60 min followed by a 60 min recovery period and, on a second occasion, cycled at 0.5 kp (kilopond), 30 rpm followed by a 60 min recovery. The ECA was measured via indirect calorimetry. Resting energy expenditure (REE), nutritional status, pulmonary function and genotype were determined. Results: The REE in patients was significantly greater than the REE measured in controls (P = 0.03) and was not related to the severity of lung disease or genotype. There was a significant difference between groups when comparing the ECA for walking kg root FFM (P = 0.001) and cycling kg root FFM (P = 0.04). The ECA for each activity was adjusted (ECA(adj)) for the contribution of REE (ECA kJ kg root FFM 120 min(-1) - REE kJ kg root FFM 120 min(-1)). ECA(adj) revealed a significant difference between groups for the walking protocol (P = 0.001) but no difference for the cycling protocol (P = 0.45). This finding may be related to the fact that the work rate during walking was more highly regulated than during cycling. Conclusions ECA in CF is increased and is likely to be explained by an additional energy-requiring component related to the exercise itself and not an increased REE. Sponsorship. The Prince Charles Hospital Foundation; MLR was in receipt of a QUTPRA Scholarship.

Transcriptional modulation of mouse mu-opioid receptor distal promoter activity by Sox18

Previously, we reported the presence of dual promoters, referred to as distal (DP) and proximal, with a negative regulatory element between them in the mouse mu -opioid receptor (mor) gene. Here we have identified a positive regulatory element influencing mor DP transcription, which contains multiple consensus binding motifs for Sox factors (sex-determining Sry-like high mobility group box-containing genes). In gel supershift assays, the Sox family member Sox18 bound directly to the multiple Sox consensus binding motifs of the mor DP enhancer. Overexpression of Sox18 cDNA increased luciferase activity regulated by the mor DP, and did so in a Sox18 concentration-dependent manner. In contrast, overexpression of another Sox member, Sox5, triggered no such trans-activation of mor DP-driven luciferase activity or DNA-protein binding activity. These results suggest that Sox18 directly and specifically stimulates mor gene expression, by trans-activating the mor DP enhancer.

Alterations in gene expression and activity during squamous cell carcinoma development

This study focuses on characterizing the genetic and biological alterations associated with squamous cell carcinoma development. Normal human epidermal keratinocytes (HEKs), cells isolated from a preneoplastic lesion (IEC-1), and two neoplastic cell lines, SCC-25 and COLD-16, were grown as raft cultures, and their gene expression profiles were screened using cDNA arrays. Our data indicated that the expression levels of at least 37 genes were significantly (P less than or equal to 0.05; 1.9% of genes screened) altered in neoplastic cells compared with normal cells. Of these genes, 10 genes were up-regulated and 27 genes were down-regulated in the neoplastic cells. In addition, 51% of the genes altered in the neoplastic cells were already altered in the preneoplastic IEC-1 cells. Immunohistochemical staining of patient tumors was used to verify the cDNA array analysis. Our analysis indicated that alterations in genes associated with extracellular matrix production and apoptosis are disrupted in preneoplastic cells, whereas later stages of neoplasia are associated with alterations in gene expression for genes involved in DNA repair or epidermal growth factor (EGF) receptor/mitogen-activated protein kinase kinase (MAPKK)/MAPK/activator protein-1 (AP-1) signaling. Subsequent functional analysis of the alterations in expression of the EGF receptor/MAPKK/MAPK/AP-1 genes suggested they did not contribute to the neoplastic phenotype.

Codon modified human papillomavirus type 16 E7 DNA vaccine enhances cytotoxic T-lymphocyte induction and anti-tumour activity

Polynucleotide immunisation with the E7 gene of human papillomavirus (HPV) type 16 induces only moderate levels of immune response, which may in part be due to limitation in E7 gene expression influenced by biased HPV codon usage. Here we compare for expression and immunogenicity polynucleotide expression plasmids encoding wild-type (pWE7) or synthetic codon optimised (pHE7) HPV16 E7 DNA. Cos-1 cells transfected with pHE7 expressed higher levels of E7 protein than similar cells transfected with pW7. C57BL/6 mice and F1 (C57X FVB) E7 transgenic mice immunised intradermally with E7 plasmids produced high levels of anti-E7 antibody. pHE7 induced a significantly stronger E7-specific cytotoxic T-lymphocyte response than pWE7 and 100% tumour protection in C57BL/6 mice, but neither vaccine induced CTL in partially E7 tolerant K14E7 transgenic mice. The data indicate that immunogenicity of an E7 polynucleotide vaccine can be enhanced by codon modification. However, this may be insufficient for priming E7 responses in animals with split tolerance to E7 as a consequence of expression of E7 in somatic cells. (C) 2002 Elsevier Science (USA).