Floral biology, pollination vectors and breeding system of Zieria granulata (Rutaceae), an endangered shrub endemic to eastern Australia

Context: Understanding the factors that influence viable-seed production is crucial in the conservation of threatened plant species, yet these factors are often poorly understood. Aims: We investigated the reproductive biology of Zieria granulata C.Moore ex Benth., an endangered Australian endemic with a limited distribution, with the intent of improving conservation and restoration outcomes. Methods: Components of floral biology, including floral ontogeny and nectar production, were quantified to determine the pollination syndrome and the likely breeding system. Flower-visitor surveys (using both digital video recordings and human observations), a manipulative wind-pollination experiment and hand-pollination experiments were conducted to investigate pollination vectors and confirm the breeding system. Key results: Z. granulata flowers were small, white, protandrous and produced highly ornamented pollen grains and small quantities of nectar; these characteristics suggest that the species fits the general entomophily syndrome. All floral visitors were arthropod species and of the 72 visitors observed, predominantly from the Dipteran and Hymenopteran families, 18 could be regarded as potential pollinators. Failure of simulated wind gusts (40 km h-1) to transport pollen ≥5 cm indicated that anemophily is unlikely for this species. Autonomous and manipulative selfing did not result in viable seed set, indicating that this is an obligate outcrossing species. However, fruit and viable-seed production was highly variable within and among some other treatments. Pre-dispersal seed predation was recorded at all study sites. Conclusions: Pre-dispersal seed predation was recorded at all study sites and is a likely factor inhibiting viable-seed production. Implications: This knowledge will be used to improve seed yield for collections used for ex situ conservation and restoration programs for the endangered Z. granulata

CD33 Alzheimer’s disease locus: Altered monocyte function and amyloid biology

In our functional dissection of the CD33 Alzheimer’s disease susceptibility locus, we find that the rs3865444C risk allele is associated with greater cell surface expression of CD33 in monocytes (t50 = 10.06, pjoint=1.3×10–13) of young and older individuals. It is also associated with (1) diminished internalization of Aβ42) (2) accumulation of neuritic amyloid pathology and fibrillar amyloid on in vivo imaging and (3), increased numbers of activated human microglia

Reproductive biology of rainforest Rutaceae : floral biology, breeding systems and pollination vectors of Acronychia oblongifolia and Sarcomelicope simplicifolia subsp. simplicifolia

The conservation of plant species requires an understanding of the factors that affect viable seed production, but often these factors are poorly understood. We investigated the reproductive biology of two Australian endemic rainforest species, Acronychia oblongifolia (A.Cunn. ex Hook.) Endl. ex Heynh and Sarcomelicope simplicifolia (Endl.) T.G.Hartley subsp. simplicifolia, with the intent of improving conservation and restoration outcomes. The floral biology of these species was quantified to provide baseline data and insights into their pollination syndrome. Flower visitor surveys (using both digital recordings and human observations), a manipulative wind pollination experiment, and hand-pollination experiments were carried out to investigate pollination vectors and determine the breeding system. Acronychia oblongifolia and Sarcomelicope simplicifolia subsp. simplicifolia were both found to best fit the general entomophily pollination syndrome. All floral visitors were arthropod species (Acronychia oblongifolia: 31; Sarcomelicope simplicifolia subsp. simplicifolia: 47) and fewer than 30% of the floral visitors identified, predominantly Diptera, Hymenoptera and Coleoptera, were regarded as potential pollinators. Failure of simulated wind gusts (40 km h-1) to transport pollen 50 cm indicated anemophily is unlikely for these species. Autonomous and manipulative selfing treatments produced few (Acronychia oblongifolia: <3%) or no (Sarcomelicope simplicifolia subsp. simplicifolia) viable seed, indicating these are predominantly outcrossing species, although fruit and viable seed production were highly variable within and among all other treatments (open to natural pollinators, pollinator exclusion, pollinator exclusion and manipulative outcross, and pollinator exclusion and manipulative selfing). Pre-dispersal seed predation was recorded for both species, at several study sites. Pre-dispersal seed predation and increased distances between compatible individuals caused by habitat fragmentation, are two factors limiting the production of viable seeds for both species