Pilbara Regions Research Articles

Root-nodule bacteria from indigenous legumes in the north-west of Western Australia and their interaction with exotic legumes

Bacteria were isolated from root-nodules collected from indigenous legumes at 38 separate locations in the Gascoyne and Pilbara regions of Western Australia. Authentication of cultures resulted in 31 being ascribed status as root-nodule bacteria based upon their nodulation of at least one of eight indigenous legume species. The authenticated isolates originated from eight legume genera from 19 sites. Isolates were characterised on the basis of their growth and physiology; 20 isolates were fast-growing and 11 were slow-growing (visible growth within 3 and 7 d, respectively). Fast-growers were isolated from Acacia, Isotropis, Lotus and Swainsona, whilst slow-growers were from Muelleranthus, Rhynchosia and Tephrosia. Indigofera produced one fast-growing isolate and seven slow-growing isolates. Three indigenous legumes ( Swainsona formosa, Swainsona maccullochiana and Swainsona pterostylis) nodulated with fast-growing isolates and four species ( Acacia saligna, Indigofera brevidens, Kennedia coccinea and Kennedia prorepens) nodulated with both fast- and slow-growing isolates. Swainsona kingii did not form nodules with any isolates. Fast-growing isolates were predominantly acid-sensitive, alkaline- and salt-tolerant. All slow-growing isolates grew well at pH 9.0 whilst more than half grew at pH 5.0, but all were salt-sensitive. All isolates were able to grow at 37 °C. The fast-growing isolates utilised disaccharides, whereas the slow-growing isolates did not. Symbiotic interactions of the isolates were assessed on three annual, one biennial and nine perennial exotic legume species that have agricultural use, or potential use, in southern Australia. Argyrolobium uniflorum, Chamaecytisus proliferus, Macroptilium atropurpureum, Ononis natrix, Phaseolus vulgaris and Sutherlandia microphylla nodulated with one or more of the authenticated isolates. Hedysarum coronarium, Medicago sativa, Ornithopus sativus, Ornithopus compressus, Trifolium burchellianum, Trifolium polymorphum and Trifolium uniflorum did not form nodules. Investigation of the 31 authenticated isolates by polymerase chain reaction with three primers resulted in the RPO1 primer distinguishing 20 separate banding patterns, while ERIC and PucFor primers distinguished 26 separate banding patterns. Sequencing the 16S rRNA gene for four fast- and two slow-growing isolates produced the following phylogenetic associations; WSM1701 and WSM1715 (isolated from Lotus cruentus and S. pterostylis, respectively) displayed 99% homology with Sinorhizobium meliloti, WSM1707 and WSM1721 (isolated from Sinorhizobium leeana and Indigofera sp., respectively) displayed 99% homology with Sinorhizobium terangae, WSM1704 (isolated from Tephrosia gardneri) shared 99% sequence homology with Bradyrhizobium elkanii, and WSM1743 (isolated from Indigofera sp.) displayed 99% homology with Bradyrhizobium japonicum.

Root-nodule bacteria from indigenous legumes in the north-west of Western Australia and their interaction with exotic legumes

Bacteria were isolated from root-nodules collected from indigenous legumes at 38 separate locations in the Gascoyne and Pilbara regions of Western Australia. Authentication of cultures resulted in 31 being ascribed status as root-nodule bacteria based upon their nodulation of at least one of eight indigenous legume species. The authenticated isolates originated from eight legume genera from 19 sites. Isolates were characterised on the basis of their growth and physiology; 20 isolates were fast-growing and 11 were slow-growing (visible growth within 3 and 7 d, respectively). Fast-growers were isolated from Acacia, Isotropis, Lotus and Swainsona, whilst slow-growers were from Muelleranthus, Rhynchosia and Tephrosia. Indigofera produced one fast-growing isolate and seven slow-growing isolates. Three indigenous legumes (Swainsona formosa, Swainsona maccullochiana and Swainsona pterostylis) nodulated with fast-growing isolates and four species (Acacia saligna, Indigofera brevidens, Kennedia coccinea and Kennedia prorepens) nodulated with both fast- and slow-growing isolates. Swainsona kingii did not form nodules with any isolates. Fast-growing isolates were predominantly acid-sensitive, alkaline- and salt-tolerant. All slow-growing isolates grew well at pH 9.0 whilst more than half grew at pH 5.0, but all were salt-sensitive. All isolates were able to grow at 37 °C. The fast-growing isolates utilised disaccharides, whereas the slow-growing isolates did not. Symbiotic interactions of the isolates were assessed on three annual, one biennial and nine perennial exotic legume species that have agricultural use, or potential use, in southern Australia. Argyrolobium uniflorum, Chamaecytisus proliferus, Macroptilium atropurpureum, Ononis natrix, Phaseolus vulgaris and Sutherlandia microphylla nodulated with one or more of the authenticated isolates. Hedysarum coronarium, Medicago sativa, Ornithopus sativus, Ornithopus compressus, Trifolium burchellianum, Trifolium polymorphum and Trifolium uniflorum did not form nodules. Investigation of the 31 authenticated isolates by polymerase chain reaction with three primers resulted in the RPO1 primer distinguishing 20 separate banding patterns, while ERIC and PucFor primers distinguished 26 separate banding patterns. Sequencing the 16S rRNA gene for four fast- and two slow-growing isolates produced the following phylogenetic associations; WSM1701 and WSM1715 (isolated from Lotus cruentus and S. pterostylis, respectively) displayed 99% homology with Sinorhizobium meliloti, WSM1707 and WSM1721 (isolated from Sinorhizobium leeana and Indigofera sp., respectively) displayed 99% homology with Sinorhizobium terangae, WSM1704 (isolated from Tephrosia gardneri) shared 99% sequence homology with Bradyrhizobium elkanii, and WSM1743 (isolated from Indigofera sp.) displayed 99% homology with Bradyrhizobium japonicum.

Videoconferencing training for those working with at-risk young people in rural areas of Western Australia.

Rural Links is a videoconference training initiative developed for those who work with at-risk young people in remote and rural regions of Western Australia. The training programme was run twice (in parallel) for two groups of participants: 17 workers from the Great Southern and South West regions of Western Australia and 15 workers from the Wheatbelt, Pilbara and Kimberley regions of Western Australia. The programme consisted of seven 2 h sessions presented over 12 weeks. Objectives of the training programme centred on increasing participants' knowledge and confidence in relation to the training topics. The initiative also aimed to enhance consultation between rural youth networks and a metropolitan-based youth mental health service (YouthLink). Analyses indicated that there were improvements in workers knowledge and confidence in relation to training topics following participation in the programme. Comparisons of the improvements made by these rural participants, who accessed training via videoconferencing, and metropolitan participants, who accessed training face to face, revealed few significant differences. Rural participants reported high levels of satisfaction, decreased feelings of professional isolation and an increased likelihood of accessing YouthLink for consultative support as a result of completing the Rural Links training programme.

Oral Health and hospitalization in Western Australian children

Over the past 20 years, the prevalence of dental disease in Western Australian children has diminished. The causes of this significant improvement in health are associated with better care models, water fluoridation and changes in lifestyle. In this study, the authors examine the reasons for hospitalization for oral health conditions in Western Australia for the calendar year 1995 using the Health Department of WA database. A total of 3,754 episodes of care (4,395 bed days) was recorded for dental conditions. Dental caries resulted in the fifth and sixth highest number of episodes of hospitalization in preschool (1-4 years) and primary-school age (5-12 years) children respectively. Abnormal tooth eruption resulted in the highest number of episodes of hospitalization in high-school age (13-17 years) children. From the age-stratified rates of hospitalization (per 1000), non-Aboriginal children were more than twice as likely to enter hospital for dental related conditions. The primary cause of this is the 15 times higher rate of hospitalization for high-school age non-Aboriginal children which clearly reflects the greater use of services for impacted third molars by the metropolitan non-Aboriginal community. Examination of the distribution by health service region revealed the hospitalization rate was significantly less than the state average for the Kimberley, Pilbara, Northern Goldfields and Wanneroo regions. These data reflect the paucity of oral health care available to residents of these regions, particularly the northwest, and does not reflect a diminished burden of disease. Similarly, the rate of hospitalization for Aboriginal children reflects population and service delivery differences particularly in regional and remote WA. These data highlight the need to develop new strategies in oral health care to target 'at risk' groups in the community, particularly new parents of young children. The preventive measures associated with good oral health in children are clearly aligned with those for good general health and can be integrated into existing health messages.

Patterns of distribution of macroinvertebrate families in rivers of north‐western Australia

Summary1. The northern half of Western Australia is a large, sparsely populated area with a climate that ranges from monsoonal in the Kimberley to arid in the Gascoyne and Pilbara regions. The aquatic invertebrate fauna is poorly known.2. Fifty‐one sites located on 14 river systems were sampled three times between August 1994 and October 1995. A total of 90 taxa, most identified to family level, were collected. The fauna was dominated by insects, which constituted 74% of the total number of taxa collected.3. Major habitats at each site were sampled separately and sites with more habitats tended to have a richer fauna. All habitats showed significant differences in taxonomic richness between regions. Family richness decreased with increasing latitude, being highest in the Kimberley region and lowest in the Gascoyne.4. Despite the differences in taxon richness between regions, community composition of the aquatic invertebrate fauna at the family level did not differ greatly. Four major groups of sites were identified by cluster analysis, based on the invertebrate families present at each site, but differences between groups were small.5. Significant temporal variation in taxon richness was found in channel habitat but not the three other habitats sampled (riffle, macrophyte, pool‐rocks). Community composition in channel habitat varied temporally among groups of sites identified by cluster analysis but the pattern was not consistent.

Changing epidemiology of methicillin-resistant Staphylococcus aureus in Western Australia.

To assess the epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) in Western Australia. Retrospective review of statutory notification data. Western Australia (WA), 1993. Notification rates, antibiotic resistance patterns and classification of isolates as imported or WA MRSA strains on the basis of antibiotic susceptibility. There were 204 notifications of MRSA, 78% of which were classified as WA MRSA. Three outbreaks of MRSA infection and colonisation occurred in separate WA hospitals. Notification rates per 100,000 were highest in the rural regions: the Kimberley (86.32), Goldfields (62.47), Mid West (37.21) and Pilbara (27.38) regions; and lowest in the metropolitan regions (5.52). All MRSA isolates were susceptible to vancomycin. Most imported strains were susceptible to amikacin, bacitracin, chloramphenicol, framycetin, fusidic acid and novobiocin, but only 23% to gentamicin. WA MRSA strains remained predominantly susceptible to all antibiotics tested, except beta-lactams, erythromycin and tetracycline, but a few strains resistant to rifampicin (1%) and fusidic acid (3%) appeared in the second half of 1993. The epidemiology of MRSA in WA is changing rapidly, with increases in both the numbers of notifications and the proportion from country regions. A new strain of MRSA (WA MRSA) that is less resistant to antibiotics than imported MRSA has emerged and is threatening the State's success in preventing establishment of MRSA in its hospitals.

Immunodominant epitopes on the NS1 protein of MVE and KUN viruses serve as targets for a blocking ELISA to detect virus-specific antibodies in sentinel animal serum

Two mosquito-borne flaviviruses, Murray Valley encephalitis (MVE) and Kunjin (KUN), are the aetiological agents of Australian encephalitis. MVE causes a severe and potentially fatal form of the disease while KUN is responsible for only a few relatively mild cases. Therefore it is important that serological tests used in flavivirus surveillance differentiate between infections with these two viruses. However, this has been hampered in the past by the close antigenic relationships between flaviviruses in traditional serological assays. An epitope blocking ELISA using MVE-specific and KUN-specific monoclonal antibodies (mAb) reacting to the non-structural protein NS1 of these viruses and a flavivirus group-specific mAb reacting to the envelope (E) protein was assessed for testing sentinel animals for seroconversion to specific flavivirus infections. Using these assays we were able to detect serum antibodies to a variety of flavivirus in laboratory infected rabbits, and naturally infected chickens and in the case of primary infections, differentiate those caused by KUN or MVE. These assays are now used routinely in our laboratory for testing chicken sera from sentinel flocks in the Kimberley and Pilbara regions of north Western Australia.

Australian encephalitis in Western Australia, 1978-1991.

To review the various clinical manifestations of Murray Valley encephalitis (MVE) or Kunjin virus encephalitis in patients in Western Australia. Review of clinical records, 1978 to 1991. Of 26 reported cases of Australian encephalitis, four were excluded from study because the patient's symptoms were not definitely associated with MVE virus or Kunjin virus infection. Two further cases of MVE were not reviewed as case records were not available. Of the remaining 20 patients, 18 had MVE and two had Kunjin virus encephalitis. Sixteen cases were in the Kimberley, a tropical region where the viruses are endemic. Four were in the subtropical Pilbara and Gascoyne regions. Thirteen of the 20 cases were in Aborigines, of whom 11 were children. The seven non-Aboriginal patients were adults. Seventeen of 20 cases were in males. The range of neurological disease and outcome was similar to that in previously reported cases, with convulsions, brainstem disease or respiratory failure in severe and fatal cases, and involvement of the spinal cord, cranial nerve or cerebellum in the moderate cases. One mild cases without neurological involvement was caused by Kunjin virus. The poor outcome in young Aboriginal children indicated that disease resulting from exposure early in life was more likely to be severe. The disease in adults, irrespective of facial background, was similar to that in cases reported previously from south-eastern Australia, but generally milder.

Foods of CorellasCacatua pastinatorin Western Australia

The contents of crops from 138 Cacatua pastinator collected throughout Western Australia were examined. Abundances of the various food items reflected the land-use where the birds were collected. In the lower south-west, C. p. pastinator ate mainly Romulea rosea bulbs with moderate amounts of Avena sativa and Poa annua seeds whereas, in the wheatbelt the most frequent food for both C. p. pastinator and C. p. gymnopsis was wheat Triricum aestivum with Emex australis, Hordeum vulgare and A. sativa as important items. The diets of C. p. gymnopsls in the Murchison and Pilbara regions, and C. p. sanguinea in the Kimberley region, were more diverse with native species predominating except for those specimens collected around towns and farms where mainly wheat, oats A. sativa or sorghum Sorghum sp. had been eaten. This and other studies, indicate that corellas have broad food preferences that enable them to exploit a wide variety of habitats including those altered by humans.

Occurrence and distribution of hepatitis B infection in the aboriginal population of Western Australia.

In 1986, the prevalences of hepatitis B surface antigen (HBsAg), and other serological markers of infection with hepatitis B virus in the Western Australian adult Aboriginal population, were estimated using a stratified random sample of 1,150 subjects. When the estimates were standardised to the age and sex distribution of the total population of aborigines aged 12 years or over, the prevalence of HBsAg was 7% (95% confidence interval 6-9%). The prevalence of any marker, that is HBsAg and/or hepatitis surface antibody (anti-HBs), was 49% (44-54%). The follow-up blood specimens obtained from three-fifths of the antigenemic subjects indicated that 96% (88-99%) were hepatitis B carriers. Male subjects had twice the prevalence of HBsAg (10%; 7-13%) when compared with females (4%; 3-6%). However, there was only a modest elevation of the prevalence of any marker in men (53%) compared with women (46%). There was evidence that the prevalence of HBsAg increased with age, but this was not the case with any marker. Geographically, there was substantial variation in hepatitis B infection rates. The Eastern Goldfields region had the highest prevalence (HBsAg 12%; any marker 66%), followed by the Kimberley, Pilbara and Central regions (HBsAg 7-9%; any marker 56-59%). The lowest rates were evident in Perth and the South West (HBsAg 3-5%; any marker 23-25%). The highest prevalence of markers in any discrete community was observed in the desert people of Warburton (HBsAg 22%; any marker 85%). These data indicate that, according to World Health Organisation criteria, the aboriginal population of Western Australia has an intermediate to high risk of infection with hepatitis B.

Prefolding and overprint magnetic signatures in Precambrian (∼2.9–2.7 Ga) Igneous rocks from the Pilbara Craton and Hamersley Basin, NW Australia

A total of 446 oriented samples have been collected from an Archaean intrusion and the Fortescue Group volcanics and intrusions in the Pilbara and Hamersley regions of northwestern Australia. The paleomagnetism and rock magnetism of these samples have been investigated using susceptibility and hysteresis properties and both alternating field (af) and thermal demagnetization. The most consistent paleomagnetic results were achieved by first applying af demagnetization and then stepwise thermal demagnetization. Evidence of the effects of lightning are widespread which accounts for the efficacy of this particular demagnetization strategy. Application of the fold test has resulted in placing significant constraints on the acquisition ages of some of the magnetizations and their corresponding pole positions. A prefolding pole position from the “Millindinna Complex,” is latitude = 11.9°S, longitude = 161.3°E (dp = 6.8°, dm = 8.4°) and is correlated with a radiometric age of 2.86±0.02 Ga. Folding in the “Millindinna Complex” occurred prior to the deposition of the Fortescue Group. New geochronological data indicate that the extrusion of the flood basalts commenced about 2.8 Ga. This provides a minimum age for the magnetization of the “Millindinna Complex.” Deformation responsible for the formation of the mobile belt separating the Pilbara and Yilgarn blocks during the Ophthalmian Orogeny has affected the Fortescue Group and produced a moderate degree of folding in the southern part of the Hamersley Basin. In the region of “Millindinna Complex” outcrop, the Fortescue Group is generally flat lying. Prefolding pole positions from the Fortescue Group are for the Mount Roe Basalt, latitude = 52.4°S, longitude = 178.0°E (dp = 6.4°, dm = 9.1°) and for the Mount Jope Volcanics, latitude = 40.5°S, longitude = 128.7°E (dp = 19.9°, dm = 20.8°). The overprint magnetization in the Mount Jope Volcanics yields a pole position, latitude = 35.0°S, longitude = 211.5°E (dp = 2.8°, dm = 5.5°) and is interpreted as having been acquired during folding relating to the formation of the Ophthalmian Fold Belt.