Putting the best foot forward: Relationships between indicators of step quality and cadence in three gait vulnerable populations.

BACKGROUND: Aging and neurological conditions like Multiple Sclerosis (MS) and Parkinson's disease (PD) make people vulnerable for gait impairments, limit function, and restrict sustained walking needed for health promotion. Walking to meet physical activity guidelines requires adequate cadence which is difficult to achieve for gait vulnerable populations. OBJECTIVE: The objective of this study is to estimate, for seniors and people with MS or PD, the extent to which cadence is associated with heel-to-toe stepping pattern (good steps), angular velocity of ankle at heel-strike and its variability. METHODS: A cross-sectional regression analysis was performed on data collected during walking tests using the Heel2Toe sensor. RESULTS: Health condition (MS = 57, PD = 27, seniors = 56) had an association with cadence, independent of age and sex. Only angular velocity showed a significant relationship with cadence such that every - 50° difference in angular velocity (more negative is better) was associated with a difference of ≈3.5 steps per minute. CONCLUSION: Adequate angular velocity occurs with an optimal heel-to-toe movement. This heel-to-toe gait can easily be targeted during therapy but technology would be an asset to sustain the relearned movement during everyday activities, Technology that provides real-time feedback for steps with adequate angular velocity at heel strike could be a valuable therapeutic adjunct.

Anticholinergic medicines in an older primary care population: a cross-sectional analysis of medicines' levels of anticholinergic activity and clinical indications.

WHAT IS KNOWN AND OBJECTIVES: Adverse clinical outcomes have been associated with cumulative anticholinergic burden (to which low-potency as well as high-potency anticholinergic medicines contribute). The clinical indications for which anticholinergic medicines are prescribed (and thus the 'phenotype' of patients with anticholinergic burden) have not been established. We sought to establish the overall prevalence of prescribing of anticholinergic medicines, the prevalence of prescribing of low-, medium- and high-potency anticholinergic medicines, and the clinical indications for which the medicines were prescribed in an older primary care population. METHODS: This was a cross-sectional analysis of a cohort study of Australian early-career general practitioners' (GPs') clinical consultations - the Registrar Clinical Encounters in Training (ReCEnT) study. In ReCEnT, GPs collect detailed data (including medicines prescribed and their clinical indication) for 60 consecutive patients, on up to three occasions 6 months apart. Anticholinergic medicines were categorized as levels 1 (low-potency) to 3 (high-potency) using the Anticholinergic Drug Scale (ADS). RESULTS: During 2010-2014, 879 early-career GPs (across five of Australia's six states) conducted 20 555 consultations with patients aged 65 years or older, representing 35 506 problems/diagnoses. Anticholinergic medicines were prescribed in 10·4% [95% CIs 9·5-10·5] of consultations. Of the total anticholinergic load of prescribed medicines ('community anticholinergic load') 72·7% [95% CIs 71·0-74·3] was contributed by Level 1 medicines, 0·8% [95% CIs 0·5-1·3] by Level 2 medicines and 26·5% [95% CIs 24·8-28·1] by Level 3 medicines. Cardiac (40·0%), Musculoskeletal (16·9%) and Respiratory (10·6%) were the most common indications associated with Level 1 anticholinergic prescription. For Level 2 and 3 medicines (combined data), Psychological (16·1%), Neurological (16·1%), Musculoskeletal (15·7%) and Urological (11·1%) indications were most common. WHAT IS NEW AND CONCLUSION: Anticholinergic medicines are frequently prescribed in Australian general practice, and the majority of the 'community' anticholinergic burden is contributed by 'low'-anticholinergic potency medicines whose anticholinergic effects may be largely 'invisible' to prescribing GPs. Furthermore, the clinical 'phenotype' of the patient with high anticholinergic burden may be very different to common stereotypes (patients with urological, psychological or neurological problems), potentially making recognition of risk of anticholinergic adverse effects additionally problematic for GPs.

The prevalence of co-prescription of clinically relevant CYP enzyme inhibitor and substrate drugs in community-dwelling elderly Australians.

WHAT IS KNOWN AND OBJECTIVE: The elderly are at increased risk of adverse effects resulting from drug interactions due to decreased drug clearance and polypharmacy. This study examines the prevalence of the co-administration of clinically relevant cytochrome P450 (CYP) enzyme inhibitors with drugs that are substrates for these enzymes, in the community-dwelling elderly in Australia. METHODS: Participants aged 75 years or older (n = 1045) were recruited via their general practitioners at four Australian sites (Newcastle, Sydney, Melbourne and Adelaide). A research nurse visited the home of each patient to compile a list of all prescription medications (including doses) currently used by the patient, and to complete assessments for depression, quality of life and cognitive status. The medication data were searched for the co-prescription of clinically relevant CYP inhibitor and corresponding substrate drugs. RESULTS AND DISCUSSION: Potentially inappropriate CYP inhibitor-substrate combinations were found in 6·2% (65/1045) of patients. These patients were on significantly more medications (6·1 ± 3·0 vs. 3·9 ± 2·5; P = 0·001) and had a significantly lower physical quality of life (P = 0·047) than those who were not on any CYP inhibitor-substrate combinations. The most commonly prescribed inhibitor-substrate combinations involved the CYP 3A4 inhibitors, diltiazem and verapamil, with the substrates simvastatin or atorvastatin. Only 1 of 41 patients on a CYP3A4 inhibitor and a statin was prescribed a non-CYP 3A4 metabolized statin. Metoprolol was another substrate commonly co-prescribed with a CYP2D6 inhibitor. In many cases, the risks and benefits of potential interactions may have been considered by the GP as the prescribed doses of both the inhibitor and substrate were relatively low. There were, however, some notable exceptions, also involving the substrates simvastatin, atorvastatin and metoprolol. There were no GP factors that were associated with co-prescription of CYP inhibitors and substrates. WHAT IS NEW AND CONCLUSION: There is not a particular GP demographic that should be targeted for education regarding CYP interactions, but a focus on particular medications such as the statins may reduce the potential for clinically significant drug-drug interactions. As CYP drug-drug interactions are more common in patients on higher number of medications, particular vigilance is required at the time of prescribing and dispensing medications for elderly patients with multiple conditions.

Improving public health information: a data quality intervention in KwaZulu-Natal, South Africa.

OBJECTIVE: To evaluate the effect of an intervention to improve the quality of data used to monitor the prevention of mother-to-child transmission (PMTCT) of the human immunodeficiency virus in South Africa. METHODS: The study involved 58 antenatal clinics and 20 delivery wards (37 urban, 21 rural and 20 semi-urban) in KwaZulu-Natal province that provided PMTCT services and reported data to the District Health Information System. The data improvement intervention, which was implemented between May 2008 and March 2009, involved training on data collection and feedback for health information personnel and programme managers, monthly data reviews and data audits at health-care facilities. Data on six data elements used to monitor PMTCT services and recorded in the information system were compared with source data from health facility registers before, during and after the intervention. Data completeness (i.e. their presence in the system) and accuracy (i.e. being within 10% of their true value) were evaluated. FINDINGS: The level of data completeness increased from 26% before to 64% after the intervention. Similarly, the proportion of data in the information system considered accurate increased from 37% to 65% (P < 0.0001). Moreover, the correlation between data in the information system and those from facility registers rose from 0.54 to 0.92. CONCLUSION: A simple, practical data improvement intervention significantly increased the completeness and accuracy of the data used to monitor PMTCT services in South Africa.

Acrosome stability in the spermatozoa of dasyurid marsupials.

The spermatozoa of most marsupials lack nuclear stabilising disulfide-bonded protamines found in eutherian mammals. However, disulfide stabilisation has been observed in the acrosome of macropodid (Macropus eugenii) and phalangerid (Trichosurus vulpecula) marsupials. As a result this organelle, which is normally fragile in eutherian mammals, is robust and able to withstand physical and chemical challenge in these marsupials. The present study examined acrosomal characteristics of the spermatozoa of three dasyurid marsupials; the fat-tailed dunnart (Sminthopsis crassicaudata), eastern quoll (Dasyurus viverrinus) and northern quoll (Dasyurus hallucatus). In all species examined Bryan's staining demonstrated that significant acrosomal loss occurred following physical challenge with osmotic stress, cryopreservation without cryoprotectant and exposure to detergent (Triton-X). Bromobimane staining indicated that the acrosomes of dasyurids lacked stabilising disulfide bonds. As reported for the wallaby and possum, calcium ionophore (A23187) did not induce the acrosome reaction-like exocytosis in dasyurid spermatozoa but treatment with diacylglycerol (DiC8) caused significant acrosome loss at concentrations similar to those effective for other marsupials. The present study found that the spermatozoa of dasyurids are more sensitive to physical challenge than the previously-studied marsupials and we suggest that this is due to the absence of acrosomal stabilising disulfide bonds.

A flow cytometric assay for global estimation of tyrosine phosphorylation associated with capacitation of spermatozoa from two marsupial species, the tammar wallaby (Macropus eugenii) and the brushtail possum (Trichosurus vulpecula).

The phosphorylation of tyrosine residues in cellular proteins is a major signal transduction event during sperm capacitation. In this study protein phosphorylation was monitored using a fluorescein isothiocyanate (FITC)-labeled antiphosphotyrosine monoclonal antibody and a flow cytometric procedure optimized for sperm. Using this technique, the correlation between tyrosine phosphorylation and sperm capacitation was examined in two marsupial species, the brushtail possum and the tammar wallaby and compared with that of ram spermatozoa. The levels of tyrosine phosphorylation in sperm from all three species were increased by the addition of cyclic AMP (cAMP) and vandate, a phosphotyrosine phosphatase inhibitor and were decreased by the addition of the phosphotyrosine kinase inhibitor, staurosporine. Oviductal conditioned media (CM) induced a progressive increase in tyrosine phosphorylation in both marsupial species and also induced morphological transition from a streamlined to a 'T'-shape configuration in brushtail possum spermatozoa but not in tammar wallaby spermatozoa. Transition to the 'T'-shape orientation associated with capacitation in marsupial spermatozoa was observed by 2 h of incubation in both species when tyrosine phosphorylation was increased by higher levels of cAMP i.e. 5 mM dibutyryl cAMP plus 3 mM pentoxyphylline. Thus the tyrosine phosphorylation trigger with CM may differ in these two marsupial species. Ram sperm tyrosine phosphorylation could be increased by addition of lower levels of cAMP (1 mM). These results support the finding that tyrosine phosphorylation is associated with sperm capacitation in marsupials. Similar results were obtained by using SDS PAGE/Western blot analysis of tyrosine phosphorylation in the brushtail possum spermatozoa. The specificity, efficiency and sensitivity of the procedure described here make it applicable for routine assessment of capacitation in large numbers of samples and in other species.

Effects of repeated superovulation and surgical oocyte collection on ovarian response and natural breeding ability of the tammar wallaby (Macropus eugenii).

The aim of this study was to assess the response of a marsupial, the tammar wallaby (Macropus eugenii) to repeated superovulation and surgical oocyte collection and monitor any effects on subsequent natural breeding ability. Animals (n = 5 per group) were superovulated once, twice or three times with pig FSH (pFSH; 6 mg administered twice per day for 4 days) followed by 4 mg pig LH (pLH). There was an interval of either 5-6 weeks (n = 9) or 12 weeks (n = 1) between the first and second superovulation and 13-17 weeks (n = 5) between the second and third superovulation. Oocytes were collected surgically after each treatment. Serum was collected at the time of each treatment to monitor the formation of anti-pFSH and anti-pLH antibodies. Animals were allowed to mate naturally in the season following superovulation treatment(s). There was no significant difference between groups in the number of large follicles (2-5 mm diameter, mean +/- standard error) produced in response to the first (21.2 +/- 4.3), second (18.0 +/- 6.5) or third (29.0 +/- 4.9) superovulation treatment. Eggs were recovered from approximately 80% of follicles that were flushed during laparotomy. There were significant concentrations of anti-pFSH and anti-pLH antibodies (P < 0.05) detected in previously superovulated animals at the time of the second superovulation but not at the time of the third superovulation. The anti-gonadotrophin antibodies present at the time of repeated superovulation did not cause a significant decrease in average number of follicles. All animals produced pouch young in the breeding seasons after repeated superovulation. Combined with other reproductive technologies, repeated superovulation has the potential to increase the production of offspring from rare or valuable marsupials in captivity.

Ionic calcium levels in oviduct explant-conditioned media from an Australian marsupial, the brushtail possum (Trichosurus vulpecula) and its relevance to in vitro fertilization.

Gametes from the brushtail possum (Trichosurus vulpecula), an Australian marsupial, require exposure to oviductal cells and/or their secretions before sperm binding and penetration of the zona pellucida can occur. Sperm-egg fusion, the next critical step in fertilization has not previously been reported in vitro. Here we describe the refinement of an oviduct epithelial cell (OEC) explant culture system using two different media to obtain in vitro sperm-egg fusion in the brushtail possum for the first time. Conditioned media from OEC explant cultures were supplemented with either 1% fetal calf serum (FCS) or 1 mg/ml polyvinyl alcohol and used for co-culture of epididymal sperm and superovulated eggs. Under these conditions zona penetration rates varied from 0 to 46% and sperm-egg fusion from 0 to 20%. Analysis of explant conditioned media indicated that qualitative and quantitative differences between batches could account, at least partially, for the large variability in zona penetration rates. Conditioned media that contained approximately 1 mM of ionic calcium were most effective for achieving sperm capacitation, zona binding, and penetration and sperm-egg fusion. The reorientation of the sperm head to T-shape, an indicator of capacitation in the brushtail possum, was closely linked with the concentration of calcium present in vitro.

Attitudes towards prenatal HIV testing and treatment among pregnant women in southern India.

During June and July 1999, oral interviews were conducted on 666 women seeking prenatal care at 9 medical facilities in Chennai and Mysore, India, to assess their attitudes towards prenatal HIV testing and antiretroviral prophylaxis for preventing perinatal HIV transmission if needed. Seventy-eight per cent were aware of the risk of perinatal HIV transmission and 36% knew that intervention could reduce the chances of such transmission. Eighty-six per cent would agree to undergo prenatal HIV testing but only 21% of all respondents would make this decision independently while 46% said their husband would have to decide. Of those women who would not agree to testing, 21% would agree if testing were compulsory. Ninety-seven per cent of respondents would undergo antiretroviral prophylaxis to prevent vertical transmission, and 94% would consider alternatives to breastfeeding if HIV positive. Considering its widespread acceptability, prenatal voluntary counselling and testing may be an affordable method of HIV prevention for this population.

Sperm binding and penetration of the zona pellucida in vitro but not sperm-egg fusion in an Australian marsupial, the brushtail possum (Trichosurus vulpecula).

Sperm capacitation and in vitro fertilisation (IVF) have been achieved in most eutherian mammals and American marsupials under relatively simple culture conditions. In contrast sperm capacitation in Australian marsupials has not been achieved in vitro and attempts at IVF have previously been characterised by a complete lack of sperm-zona pellucida (ZP) binding. Recently, co-culture of sperm with oviduct epithelial cell monolayers or with oviductal explant conditioned media has been shown to prolong the viability and motility of brushtail possum spermatozoa, as well as to induce capacitation-associated changes such as transformation of sperm to the T-shape orientation. In this study we report that these in vitro produced T-shaped sperm, and in vivo derived T-shaped sperm flushed from the oviduct of artificially inseminated possums as a control, are able to bind to and penetrate the ZP of approximately 25% of eggs recovered from PMSG/LH-superovulated possums in vitro. Development of ZP receptivity and penetrability towards sperm was also identified as a major factor affecting the outcome of IVF. Neither in vivo nor in vitro derived T-shaped sperm were able to bind to or penetrate the ZP if eggs were obtained from animals that were treated with pLH less than 76 h after PMSG. Thus this study provides preliminary evidence for the necessity of sperm-oviduct epithelial cell interactions for capacitation in Australian species and lends further support to the suggestion that the T-shape head orientation is indicative of sperm capacitation. Despite the occurrence of sperm-ZP binding and penetration, sperm-egg membrane fusion and egg activation were not observed. Although the factor(s) responsible for the lack of sperm-egg membrane fusion in the possum have not been identified it is possible that egg capacity for membrane fusion develops independently of zona receptivity and is defective in these eggs, or alternatively that membrane fusion requires strictly defined ionic conditions which are not provided by the IVF media used in this study.

Induction of thumbtack sperm during coculture with oviduct epithelial cell monolayers in a marsupial, the brushtail possum (Trichosurus vulpecula).

A reorientation of the sperm head so that it is perpendicular to the sperm tail (i.e., T-shape or thumbtack) is considered an indicator of sperm capacitation in the Australian marsupial the brushtail possum (Trichosurus vulpecula). This study describes a method of oviduct epithelial cell monolayer and sperm coculture in the brushtail possum to obtain a high percentage of thumbtack sperm. The oviduct epithelial cell (OEC) monolayers were prepared in vitro from the isthmal and ampullary segments of eCG- and LH-primed brushtail possum oviducts. Coculture experiments demonstrated that cauda epididymidal sperm from the brushtail possum attached equally to the OEC monolayers derived from the isthmal and ampullary segments of the oviduct. After 2 h of coculture, a large number of sperm attached to OEC monolayers (ampulla, 60.1+/-4.7% and isthmus, 63.1+/-5.7%) as well as to controls (tracheal epithelial cell monolayer, 46.2+/-3.7%; Matrigel, 57.4+/-7.7%; plastic, 29.2+/-3.2%). After 6 h, fewer sperm were attached to tracheal epithelial cell monolayers (1.2+/-0.2%; P<0.01) and Matrigel (10.2+/-2.5%; P<0.01), compared to those attached to ampullary and isthmal OEC monolayers (37.9+/-7.2% and 44.6+/-2.2%, respectively), and none were attached to the plastic surface. Fewer sperm were released from the ampullary and isthmal OEC monolayers compared to those from controls (P<0.05). At 6 h of coculture with ampullary and isthmal OEC, the percentage motility of both attached and unattached spermatozoa was maintained at 40-50%, which was higher (P<0.05) than in controls. Progressive motility of unattached sperm was maintained at about 2 (on an arbitrary scale of 1-5) and was not different among treatments until 6 h. More than 60-70% sperm were viable at 6 h of coculture in all the treatments. Coculture of brushtail possum epididymal sperm with OEC monolayers transformed 60% of motile streamlined spermatozoa to thumbtack orientation at 2 h compared to approximately 25% in controls. No acrosomal modifications were induced in spermatozoa in any of the treatments. This study has demonstrated a role of the oviduct in transforming a large number of sperm from a streamlined to thumbtack orientation, which may have relevance in sperm capacitation and fertilization in this species.

Cloning and characterisation of a zona pellucida 3 cDNA from a marsupial, the brushtail possum Trichosurus vulpecula.

The mammalian zona pellucida (ZP) is an extracellular glycoprotein coat that plays vital roles throughout fertilisation and preimplantation development. Like that of eutherian mammals the brushtail possum ZP is composed of three glycosylated proteins of 137 kDa, 92 kDa and 62 kDa. The 62 kDa protein is a ZP3 orthologue based on its nucleotide and deduced amino acid sequence. The brushtail possum ZP3 cDNA isolated in this study is 1305 nucleotides with an open reading frame encoding a 422 amino acid peptide of 45.7 kDa. Possum ZP3 has a 46% amino acid identity with eutherian ZP3 and shares similar structural characteristics including 12 conserved cysteine residues, N-linked glycosylation sites and hydrophobic regions. Like human and rabbit ZP1 an altered furin cleavage site upstream of the C-terminal hydrophobic domain also occurs in possum ZP3 (S-R-K-R), suggestive of processing by a furin-related endoprotease. Expression of brushtail possum ZP3 is limited to the ovary. Characterisation of brushtail possum ZP3 will enable examination of its functional role in marsupial fertilisation and its effectiveness as an immunocontraceptive agent.

Secretory proteins from the female reproductive tract of the brushtail possum (Trichosurus vulpecula): binding to sperm and effects on sperm survival in vitro.

Previous studies have demonstrated that co-culture of brushtail possum epididymal spermatozoa with oviduct epithelial cell monolayers prolongs sperm survival and results in the re-orientation of the sperm head and tail to the T-shape (thumbtack) configuration. Transformation of sperm to thumbtack orientation is believed to be associated with marsupial sperm capacitation. Here we report that incubation in oviduct-conditioned media also significantly prolongs sperm survival and results in the transformation of sperm to the thumbtack orientation. The major objective of the current study was to examine the proteins present in the conditioned media, to determine whether any of these proteins specifically bound to sperm and the relationship between these proteins and sperm survival and thumbtack orientation. Co-culturing brushtail possum sperm with biotin-labeled proteins in conditioned media (CM) from ampulla, isthmus and uterine explants demonstrated strong binding of two proteins of molecular mass 230 and 61 kD and weak binding of nine proteins of molecular mass 200, 180, 120, 140, 55, 52, 48, 34, 30 kD to sperm within 30 min. The binding of the 61-kD protein from the conditioned media appeared specific as increasing concentrations of non-labeled oviduct proteins, but not serum proteins, inhibited the binding of labeled proteins. The binding of oviduct and uterine proteins in the conditioned media significantly prolonged sperm survival and percentage motility and also transformed a large number of sperm to a thumbtack orientation. The implication of binding of these proteins is discussed in the context of sperm survival and capacitation in this species.

Timing and regulatory aspects of oocyte maturation in vitro in the tammar wallaby (Macropus eugenii).

Oocytes from a marsupial, the tammar wallaby (Macropus eugenii), resemble those of eutherian mammals in their ability to resume meiosis in vitro when cultured under suitable conditions. Culture for 42-48 h in Eagle's minimum essential medium (EMEM) supplemented with 10% fetal calf serum, and 10 microg mL(-1) porcine luteinizing hormone (pLH) was required in order for oocytes, collected from the large antral follicles (> 2 mm diameter) of tammar wallabies (primed with 6 mg of porcine follicle stimulating hormone twice daily for four days), to proceed to metaphase II (MII) of meiosis. Under these conditions, chromatin condensation was observed within 4-8 h of culture in 61% of oocytes; metaphase I (MI) chromosomes were observed from 18-30 h of culture (66%); and most oocytes (76%) progressed to MII by 42 h in vitro. The addition of cycloheximide, a protein synthesis inhibitor, at concentrations of 1-100 microg mL(-1), prevented maturation of tammar wallaby oocytes in vitro. This effect was reversible, as oocytes washed free of cycloheximide after 4 h of incubation were able to progress to MII. The addition of cycloheximide to wallaby oocytes at MI of meiosis prevented normal progression to MII suggesting that proteins critical for nuclear maturation are synthesized throughout the maturation process. Genistein, a protein kinase inhibitor decreased maturation of wallaby oocytes in a dose dependent manner. However, the concentration required to significantly inhibit maturation of wallaby oocytes (60 microg mL(-1)) was greater than that required for eutherian species. Most wallaby oocytes were able to undergo germinal vesicle breakdown (GVBD) in the presence of high concentrations of genistein but produced abnormal chromatin configurations and were unable to progress to MII. Future studies will examine whether cytoplasmic changes occur in marsupial oocytes in vitro and their temporal relationship to nuclear maturation.

Manipulation of the fertility of marsupials for conservation of endangered species and control of over-abundant populations.

Marsupials present a dichotomy in population management; the numbers of many Australian marsupial species have declined due to loss of habitat, competition from introduced herbivores and predation by introduced carnivores, but other species have become locally overabundant in Australia or are introduced pests in New Zealand. The manipulation of reproduction offers the means to increase or decrease productivity; however, considerable fundamental research is required before reproductive technologies can be applied to marsupials. Marsupials differ from eutherian mammals in several aspects of their reproduction including sex differentiation, gamete function and endocrinology, as well as in the relative lengths of gestation and lactation. Although these differences present unique problems in the application of reproductive technologies to marsupials, they also present unique opportunities for marsupial-specific fertility control. This paper summarises the assisted breeding technologies currently being applied to marsupials including superovulation, artificial insemination, in vitro fertilization and gene banking; unique marsupial targets for contraceptive intervention including gamete production, sperm capacitation, gamete surface antigens and embryonic development; and some options for the delivery of contraceptive vaccines to marsupial populations.

Timing of zona pellucida formation in the tammar wallaby (Macropus eugenii) and brushtail possum (Trichosurus vulpecula).

The zona pellucida (ZP) is an extracellular coat that surrounds the mammalian egg, and serves as the primary recognition site for fertilizing spermatozoa. The timetable of ZP formation was examined in two marsupials, the tammar wallaby (Macropus eugenii) and the brushtail possum (Trichosurus vulpecula) using conventional histological methods, immunofluorescence and electron microscopy. Ovaries from tammar wallaby pouch young less than 80 days of age contained only primordial follicles with a single layer of flattened granulosa cells. There was no evidence of ZP formation until 98 days, when a small number of eggs surrounded by a single layer of cuboidal granulosa cells had a ZP detectable by periodic-acid-schiff staining and rabbit anti-pig ZP polyclonal antibody labelling. Possum ovaries at 108 and 114 days also contained a small number of eggs with a ZP and a single layer of cuboidal granulosa cells. The antibody also labelled the peripheral cytoplasm of oocytes at this stage and, occasionally, the granulosa cells. Antral follicles were first detected at 144 days in the wallaby and 125 days in the possum, and always contained an egg surrounded by a ZP. Ovaries from 147, 158, 165, 181, 184 and 210-day-old tammar wallabies contained a range of follicle types from primordial through early antrum formation. Electron microscopy confirmed observations made at the light microscope level. The ZP was first detectable in small primary follicles with a single layer of cuboidal granulosa cells in areas where microvilli had begun to form on the egg plasma membrane. Immunogold labelling indicated the egg cytoplasm as the origin of the ZP proteins. The ZP completely filled the space between the egg and the adjacent granulosa cells in preantral follicles, so that there was no perivitelline space.

Sequence and analysis of zona pellucida 2 cDNA (ZP2) from a marsupial, the brushtail possum, Trichosurus vulpecula.

All mammalian eggs are surrounded by the zona pellucida, an extracellular coat involved in vital functions during fertilization and early development. The zona pellucida glycoproteins are promising antigenic targets for development of contraceptive vaccines to control pest populations of marsupials in Australia and New Zealand. Our current understanding of the function of the zona pellucida glycoproteins is based almost entirely on the mouse and may not be representative of gamete interactions in all eutherian or marsupial mammals. This study reports the isolation and characterization of the ZP2 gene from the brushtail possum (Trichosurus vulpecula). The brushtail possum ZP2 mRNA is 2,182 nucleotides long with an open reading frame coding for a polypeptide chain of 712 amino acids with a molecular mass of 79,542 d. The deduced amino acid sequence of possum ZP2 is 48 to 55% identical to that of eutherian mammals. It shares several structural characteristics including N-linked glycosylation sites, location and number of cysteine residues, and hydropathy profile. The brushtail possum ZP2 gene is expressed exclusively in the ovary. Further studies are planned to elucidate the specific site of ZP2 expression within the ovary and its function during fertilization in marsupials.

Sperm-oviduct epithelial cell monolayer co-culture: an in vitro model of sperm-female tract interactions in a marsupial, the tammar wallaby (Macropus eugenii).

Oviduct epithelial cell (OEC) monolayers were prepared from the isthmic and ampullary parts of the oviducts of FSH-primed tammar wallabies. Co-culture experiments found that 50-60% of wallaby spermatozoa attached immediately to OEC monolayers, tracheal cell monolayer controls, and the surface of culture dishes with and without Matrigel coating. Spermatozoa were considered to be attached if they remained on the culture surface after rapidly pipetting the co-culture medium five times. The percentages of attached and unattached spermatozoa were calculated from the number of spermatozoa recovered in the agitated supernatant. After 2 h co-culture the percentage of attached spermatozoa rose to 60-80%. After 6 h co-culture the number of spermatozoa attached to OEC monolayers derived from the oviductal isthmus remained high and only a small percentage were recovered in the agitated supernatant (unattached spermatozoa 3.85 +/- 0.76%, P = 0.67). However, after 6 h co-culture of spermatozoa with OEC monolayers derived from the ampulla and with the controls the percentage of attached spermatozoa declined significantly (unattached spermatozoa: ampullary monolayer 23.08 +/- 4.80%, P < 0.01; tracheal monolayer 23.23 +/- 5.18%, P < 0.01; Matrigel 27.23 +/- 7.76%, P < 0.01; plastic surface 28.19 +/- 5.30%, P < 0.01). After 6 h co-culture with ampullary and isthmic OEC monolayers, the percentage motility of both attached and unattached spermatozoa was maintained at 64.00 +/- 1.90% and 56.66 +/- 3.18% and 62.00 +/- 3.11% and 52.00 +/- 2.43%, respectively, and was then maintained at > or = 35% after 24 h incubation. In the controls, that is, tracheal monolayer and Matrigel, the motility of attached spermatozoa declined rapidly to 48.66 +/- 2.15% and 33.63 +/- 8.66%, respectively, at 6 h, and all spermatozoa were immotile after 24 h incubation. However, the motility of unattached spermatozoa in the controls (tracheal monolayer and Matrigel) was maintained at 57.33 +/- 3.00% and 34.54 +/- 9.27%, respectively, until 6 h and then declined rapidly, and all spermatozoa were immotile after 24 h incubation. Co-culture of wallaby spermatozoa with OEC monolayers also induced acrosomal modifications that were followed by acrosomal loss. At 6 h incubation 38.92 +/- 3.98% of spermatozoa on ampullary OEC monolayers and 36.50 +/- 3.81% spermatozoa on isthmic OEC monolayers had shed their acrosome. Acrosomal loss during co-culture with both isthmic and ampullary OEC monolayers was significantly (P < 0.01) greater than that observed on tracheal epithelial monolayer (24.42 +/- 1.90%, P < 0.01), Matrigel (20.70 +/- 2.71%, P < 0.01) and plastic (15.54 +/- 2.49%, P < 0.01). Co-culturing spermatozoa with OEC monolayers also induced a transformation from streamlined orientation of sperm head and tail to T-shaped (thumbtack) orientation in a small number (10-15%) of motile spermatozoa after 6 h incubation (data not shown). The significance of these results in relation to the role of the oviduct in sperm capacitation is discussed.

Cytoplasmic maturation of the marsupial oocyte during the periovulatory period.

During the period immediately before ovulation, the oocytes of most eutherian and marsupial mammals complete the first meiotic maturation division and extrude the first polar body. In marsupials, this phase of nuclear maturation is accompanied by an increase in size of the egg and maturation of cytoplasmic components. Oocytes from at least four marsupial species, Trichosurus vulpecula, Macropus eugenii, Bettongia penicillata and Monodelphis domestica, continue to grow after formation of the follicular antrum and, although the rate of growth slows in larger follicles, it continues into the period immediately before ovulation. The basis of this growth is unknown but may include accumulation of fluid and/or yolk-like material. Maturational changes within the cytoplasm of the oocyte also occur during the periovulatory period, including the accumulation of cortical granules. Differences in the structure of the zona pellucida are also evident between follicular and ovulated eggs; these differences are suggestive of compression of the zona pellucida, but may involve the addition of extra material. These findings suggest that the marsupial oocyte may not achieve complete cytoplasmic maturity until after ovulation; however, their relevance to fertilization and embryonic development require further investigation. Like those of eutherian mammals, marsupial oocytes undergo spontaneous nuclear maturation once removed from the follicular environment, suggesting a basically similar control system. It is not known whether the preovulatory cytoplasmic changes seen in marsupial oocytes matured in vivo also occur during maturation in vitro.