Thresholds of Toxicological Concern for Cosmetics-Related Substances: New Database, Thresholds, and Enrichment of Chemical Space

A new dataset of cosmetics-related chemicals for the Threshold of Toxicological Concern (TTC) approach has been compiled, comprising 552 chemicals with 219, 40, and 293 chemicals in Cramer Classes I, II, and III, respectively. Data were integrated and curated to create a database of No-/Lowest-Observed-Adverse-Effect Level (NOAEL/LOAEL) values, from which the final COSMOS TTC dataset was developed. Criteria for study inclusion and NOAEL decisions were defined, and rigorous quality control was performed for study details and assignment of Cramer classes. From the final COSMOS TTC dataset, human exposure thresholds of 42 and 7.9 μg/kg-bw/day were derived for Cramer Classes I and III, respectively. The size of Cramer Class II was insufficient for derivation of a TTC value. The COSMOS TTC dataset was then federated with the dataset of Munro and colleagues, previously published in 1996, after updating the latter using the quality control processes for this project. This federated dataset expands the chemical space and provides more robust thresholds. The 966 substances in the federated database comprise 245, 49 and 672 chemicals in Cramer Classes I, II and III, respectively. The corresponding TTC values of 46, 6.2 and 2.3 μg/kg-bw/day are broadly similar to those of the original Munro dataset

The Functions of Auxilin and Rab11 in Drosophila Suggest That the Fundamental Role of Ligand Endocytosis in Notch Signaling Cells Is Not Recycling

Notch signaling requires ligand internalization by the signal sending cells. Two endocytic proteins, epsin and auxilin, are essential for ligand internalization and signaling. Epsin promotes clathrin-coated vesicle formation, and auxilin uncoats clathrin from newly internalized vesicles. Two hypotheses have been advanced to explain the requirement for ligand endocytosis. One idea is that after ligand/receptor binding, ligand endocytosis leads to receptor activation by pulling on the receptor, which either exposes a cleavage site on the extracellular domain, or dissociates two receptor subunits. Alternatively, ligand internalization prior to receptor binding, followed by trafficking through an endosomal pathway and recycling to the plasma membrane may enable ligand activation. Activation could mean ligand modification or ligand transcytosis to a membrane environment conducive to signaling. A key piece of evidence supporting the recycling model is the requirement in signaling cells for Rab11, which encodes a GTPase critical for endosomal recycling. Here, we use Drosophila Rab11 and auxilin mutants to test the ligand recycling hypothesis. First, we find that Rab11 is dispensable for several Notch signaling events in the eye disc. Second, we find that Drosophila female germline cells, the one cell type known to signal without clathrin, also do not require auxilin to signal. Third, we find that much of the requirement for auxilin in Notch signaling was bypassed by overexpression of both clathrin heavy chain and epsin. Thus, the main role of auxilin in Notch signaling is not to produce uncoated ligand-containing vesicles, but to maintain the pool of free clathrin. Taken together, these results argue strongly that at least in some cell types, the primary function of Notch ligand endocytosis is not for ligand recycling

Comparative population genetic structure of the endangered southern brown bandicoot, Isoodon obesulus, in fragmented landscapes of Southern Australia

Genetic connectivity is a key factor for maintaining the persistence of populations in fragmented landscapes. In highly modified landscapes such us peri-urban areas, organisms' dispersal among fragmented habitat patches can be reduced due to the surrounding matrix, leading to subsequent decreased gene flow and increased potential extinction risk in isolated sub-populations. However, few studies have compared within species how dispersal/gene flow varies between regions and among different forms of matrix that might be encountered. In the current study, we investigated gene flow and dispersal in an endangered marsupial, the southern brown bandicoot (Isoodon obesulus) in a heavily modified peri-urban landscape in South Australia, Australia. We used 14 microsatellite markers to genotype 254 individuals which were sampled from 15 sites. Analyses revealed significant genetic structure. Our analyses also indicated that dispersal was mostly limited to neighbouring sites. Comparisons of these results with analyses of a different population of the same species revealed that gene flow/dispersal was more limited in this peri-urban landscape than in a pine plantation landscape approximately 400 km to the south-east. These findings increase our understanding of how the nature of fragmentation can lead to profound differences in levels of genetic connectivity among populations of the same species.You Li, Steven J.B. Cooper, Melanie L. Lancaster, Jasmin G. Packer, Susan M. Carthe

Breeding system and fruit development in Persoonia juniperina (Proteaceae)

Experimental hand pollinations were used to examine factors that influence fruit production in Persoonia juniperina (Proteaceae). Assessment of the breeding system indicated no clear pre-zygotic barriers to self-fertilisation. Rates of pollen tube growth and numbers of pollen tubes were similar after selfing and outcrossing. Plants also clearly had the capacity to produce fruit from selfing, although there was some evidence of inhibition in the development of selfed zygotes. More fruit were initiated after cross-pollination, and rates of abortion were greater after selfing, resulting in lower final fruit set. Inhibition of selfed fruit is most probably exhibited post-zygotically since the percentage of ovules penetrated did not differ between treatments. However, at this stage it is difficult to differentiate between late-acting self-incompatibility and genetic load. Supplementary hand pollinations did not increase numbers of pollen tubes or percentage fruit set above natural levels, indicating that plants in the population were not pollen limited. These results contrast with those found in most other species of Proteaceae

Prey selection by the dasyurid Ningaui yvonneae

Copyright © CSIRO 2007We know little about the availability of potential prey and patterns of prey consumption by Ningaui yvonneae in a natural environment. This information is important to understanding how the species is able to exploit its semiarid environment. Here, we examine the diet of N. yvonneae inhabiting a semiarid mallee community in South Australia using a combination of faecal analysis and observations of nocturnally foraging animals. Prey consumption was compared with the availability of prey types in the environment, and comparisons made between habitat components, across seasons and between sexes. N. yvonneae was found to include a range of prey types in its diet, with 11 invertebrate taxa recorded from direct observation and eight of these detected in the scats. Prey taxa consumed most often by freely foraging ningauis were Araneae, Blattodea and Orthoptera, while those most commonly detected in scats were Hymenoptera and Araneae. In comparison, 22 invertebrate taxa were recorded in pitfall traps, although many of these were recorded infrequently. Taxa most commonly recorded in traps were Hymenoptera, Collembola, Coleoptera and Acariformes. Observational data also indicated that consumption of prey taxa differed significantly between sexes and among seasons. Males generally consumed a more diverse array of prey, with both observational and scat data showing that they were more likely to consume Hymenoptera and Isoptera, while females were more likely to consume Lepidoptera and Hemiptera. Variability between seasons was evident in consumption of invertebrate grubs (recorded only during ‘growth’; February–April), Orthoptera (recorded most often during ‘breeding’, August–October), and Araneae (recorded more often during ‘maturation’, May–July). However percentage occurrence data from the scats lacked this seasonality, possibly because of the smaller array of prey taxa recorded. N. yvonneae captured prey from all available habitat components, with five of the most frequently recorded prey taxa being recorded from all components. Leaf litter and Triodia were the most commonly recorded capture sites (45% and 22% of captures respectively), and males and females used the habitat components in a similar manner. Although N. yvonneae is like many other dasyurids in having a largely generalist insectivorous diet, comparisons of prey consumed with their availability in the environment indicated that individuals did show some selectivity towards certain taxa, particularly Blattodea, Orthoptera, Chilopoda, Lepidoptera and Araneae.Darren Bos and Susan M. Carthewhttp://www.publish.csiro.au/nid/144/paper/WR07001.ht

Patterns of movement in the small dasyurid (Ningaui yvonneae)

The movement behaviour of a small dasyurid (Ningaui yvonneae) was investigated using mark–recapture data collected over 28 months from a population in the Middleback Ranges, South Australia. We were particularly interested in assessing variability in patterns of movement between the sexes and across seasons, as this has potentially important implications for population composition and dynamics. The species was found to be fairly mobile, with frequent and sometimes large movements relative to the size of the animal (up to 900+ m). Average distances moved between recaptures within and between trap sessions were 84 m and 160 m respectively, with nearly half of all recorded movements being between trapping grids (i.e. >80 m). Relatively high recapture rates (many separated by more than 100 days) and measures of site fidelity indicated that the species was not particularly transitory, but probably establishes large and/or drifting home ranges. However, patterns of movement varied considerably according to sex and the time of year. Female N. yvonneae were generally more sedentary than males, with few females moving between trapping grids, and most short-term movements (<100 days apart) being less than 70 m. Movements of females for which the records were separated by more than 100 days tended to be larger, with an average between-capture distance >200 m. In contrast, males often moved between trapping grids, even over short periods. Some short-term movements were more than 600 m in length, and the average distance moved within trapping sessions was >100 m. During the breeding season, males more than doubled the average distances moved between recaptures, when they were presumably roaming in search of females. For females, movement distances were similar during the prebreeding and breeding seasons, but were significantly smaller in the postbreeding season, when they were caring for young.Darren G. Bos and Susan M. Carthe

Straddling the divide: den use by brushtail possums (Trichosurus vulpecula) in urban parklands

In Australia, brushtail possums (Trichosurus vulpecula) are declining in natural habitats but have adapted to urban environments so readily that some human residents consider them to be a nuisance. Although this situation represents a conundrum for management, the use of urban habitats by the species remains poorly studied. We conducted our study in six urban parklands, a setting that represents an intermediary between a fully-urban and fully-natural environment. To determine factors that influence the presence of hollows in trees and their use by brushtail possums, physical characteristics of 240 mature trees in six parks in the Adelaide Parklands, South Australia were assessed. To investigate hollow use more comprehensively, 18 possums were radio-tracked. Presence of hollows in trees was a function of tree species and tree size, with hollows formed in both exotic and native species. Tree form and number of hollows were significant predictors of the use of hollow-bearing trees by possums. Use of exotic trees was high, with only 34 % of recorded den trees being native (non-indigenous) species. Radio-tracked individuals were relatively sedentary, with an average daytime denning area of 0.08 ha. While the majority of animals used multiple den sites, all individuals favoured a single den. Use of a variety of anthropogenic structures was high, even when trees were available. On average, sites supported ~1.5 brushtail possums per hollow-bearing tree. A correlation between number of hollows per hectare and possum density (r =0.892, P =0.017) suggests that altering a given area’s density of hollows or anthropogenic structures could influence the density of possums within it