Pollination by sexual deception promotes outcrossing and mate diversity in self-compatible clonal orchids.

The majority of flowering plants rely on animals as pollen vectors. Thus, plant mating systems and pollen dispersal are strongly influenced by pollinator behaviour. In Australian sexually deceptive orchids pollinated by male thynnine wasps, outcrossing and extensive pollen flow is predicted due to floral deception, which minimizes multiple flower visitations within patches, and the movement of pollinators under mate-search rather than foraging behaviours. This hypothesis was tested using microsatellite markers to reconstruct and infer paternity in two clonal, self-compatible orchids. Offspring from naturally pollinated Chiloglottis valida and C. aff. jeanesii were acquired through symbiotic culture of seeds collected over three seasons. In both species, outcrossing was extensive (tm  = 0.924-1.00) despite clone sizes up to 11 m wide. The median pollen flow distance based on paternity for both taxa combined was 14.5 m (n = 18, range 0-69 m), being larger than typically found by paternity analyses in other herbaceous plants. Unexpectedly for orchids, some capsules were sired by more than one father, with an average of 1.35 pollen donors per fruit. This is the first genetic confirmation of polyandry in orchid capsules. Further, we report a possible link between multiple paternity and increased seed fitness. Together, these results demonstrate that deceptive pollination by mate-searching wasps enhances offspring fitness by promoting both outcrossing and within-fruit paternal diversity.

Mismatch repair protein expression in ovine intestinal adenocarcinomas.

Sheep in New Zealand develop small intestinal adenocarcinomas more frequently than sheep elsewhere in the world. This high rate of neoplasm development could be due to a genetic predisposition or due to an environmental carcinogen. Differentiation between a genetic and an environmental factor is important as, if an environmental carcinogen is present, people could be exposed directly or by consuming sheep meat. In humans, germline defects in the mismatch repair (MMR) genes cause hereditary nonpolyposis colorectal cancer (HNPCC). Affected people are predisposed to neoplasm development, most commonly colonic adenocarcinomas. It was hypothesized that MMR defects are common within the New Zealand sheep flock, and these defects predispose New Zealand sheep to intestinal neoplasia. To investigate this, immunohistochemistry was used to evaluate the expression of the MMR proteins MSH2, MSH6, MLH1, and PMS2 within 49 ovine intestinal adenocarcinomas. Neoplastic cells within all sheep tumors expressed MSH2, MSH6, and MLH1. Expression of PMS2 could not be assessed, most likely because of insufficient affinity of the anti-human PMS2 antibody to ovine PMS2. The consistent expression of MSH2, MSH6, and MLH1 within the ovine intestinal adenocarcinomas does not support the hypothesis that defects in the MMR genes are common in New Zealand sheep.

Familial adenomatous polyposis and duodenal lymphoma: report of a case.

The occurrence of duodenal polyposis is well recognized in familial adenomatous polyposis. Lymphoid hyperplasia in association with familial adenomatous polyposis usually occurs in the terminal ileum, but it can occur in the duodenum and may be endoscopically difficult to distinguish from an adenoma. A case report is presented in which a 54-year-old male with familial adenomatous polyposis, who 20 years earlier had a subtotal colectomy and ileorectal anastomosis, presented with a large rectal villous tumor and was found to have a duodenal extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue. The role of lymphoid hyperplasia in the development of mucosa-associated lymphoid tissue lymphoma is discussed, as well as the issue of mucosa-associated lymphoid tissue lymphoma in familial adenomatous polyposis. In cases in which biopsies of polypoid lesions in patients with familial adenomatous polyposis show dense lymphoid aggregates, flow cytometry may assist in the diagnosis.

Adult coeliac disease: prevalence and clinical significance.

BACKGROUND AND AIMS: Although coeliac disease is a common condition, the role of population screening is not clear. The aim of this study was to determine the prevalence and clinical significance of coeliac disease in the adult population of Christchurch, New Zealand. METHODS: A total of 1064 adults randomly selected from the 1996 Christchurch electoral rolls were enlisted. The subjects were screened for coeliac disease using the anti-endomysial antibody test (EMA), and all those with positive tests were reviewed and underwent a small bowel biopsy. RESULTS: Twelve of the 1064 persons tested (1.1%) were EMA positive and all had small bowel biopsy histology consistent with coeliac disease. Two of the 12 subjects were previously known to be EMA positive although neither had a small bowel biopsy. One additional subject with known and treated coeliac disease was also enrolled but was EMA negative. Thus, the overall prevalence of coeliac disease was 13 of 1064 subjects (1.2%, or 1:82), 10 of whom were newly diagnosed (0.9%, or 1:106) and three were previously known or suspected to have coeliac disease (0.3%, or 1:355). The prevalence in both sexes was similar. Nine of the 12 EMA-positive coeliac disease subjects identified by the use of screening reported symptoms, of which tiredness and lethargy were the most common. The subjects were of normal stature, although females tended to be lean. None of the subjects were anaemic, but four were iron deficient and four folate deficient. Five of the 12 had sustained bone fractures. Bone mineral density was reduced in males but not in females. CONCLUSIONS: The prevalence of coeliac disease in the adult population of Christchurch, New Zealand, is 1.2%. Unrecognized coeliac disease which was detected by population screening was three-fold more common than proven or suspected coeliac disease. Population screening may identify subjects who could benefit from treatment.