Structural function and evolution of the subarctometatarsus

Compares the metatarsal structural design (subarctometatarsus) of recently discovered Chinese feathered dinosaurs with the metatarsus (arctometatarsus) possessed by more advanced theropod dinosaurs and the metatarsus of more primitive forms. The subarctometatarsus was proved to be an intermediate structure. Additionally the metatarsus appears to co-incide with the evolution of the avian feather suggesting a possible relationship between the subarctometatarsus's evolution and the evolution of avian flight.

Mid-Holocene (4200 kyr BP) mass mortalities in Mauritius (Mascarenes): insular vertebrates resilient to climatic extremes but vulnerable to human impact

In the light of the currently increasing drought frequency and water scarcity on oceanic islands, it is crucial for the conservation of threatened insular vertebrates to assess how they will be affected. A 4000 yr old fossil assemblage in the Mare Aux Songes (MAS), southwest Mauritius, Mascarene Islands, contains bones of 100 000+ individual vertebrates, dominated by two species of giant tortoises Cylindraspis triserrata and C. inepta, the dodo Raphus cucullatus, and 20 other vertebrate species (Rijsdijk, Hume, Bunnik, Florens, Baider, Shapiro et al. (2009) Mid-Holocene vertebrate bone Concentration-Lagerstätte on oceanic island Mauritius provides a window into the ecosystem of the dodo (Raphus cucullatus). Quaternary Science Reviews 28: 14–24). Nine radiocarbon dates of bones statistically overlap and suggest mass mortality occurred between 4235 and 4100 cal. yr BP. The mortality period coincides with a widely recognized megadrought event. Our multidisciplinary investigations combining geological, paleontological and hydrological evidence suggests the lake was located in a dry coastal setting and had desiccated during this period. Oxygen isotope data from a Uranium-series dated stalagmite from Rodrigues, an island 560 km east of Mauritius, supports this scenario by showing frequently alternating dry and wet periods lasting for decades between 4122 and 2260 cal. yr BP. An extreme drought resulted in falling water-tables at MAS and elsewhere on the island, perhaps deprived these insular vertebrates of fresh water, which led to natural mass mortalities and possibly to extirpations. In spite of these events, all insular species survived until at least the seventeenth century, confirming their resistance to climatic extremes. Despite this, the generally exponential increase of combined human impacts on islands including loss of geodiversity, habitats, and stocks of fresh water, there will be less environmental safe-haven options for insular endemic and native vertebrates during future megadrought conditions; and therefore will be more prone to extinction.

First fossil finds of some Australian Bryozoa (Cheilostomata)

The abundant fossil record of well-preserved Bryozoa in samples from the Tertiary of Victoria and South Australia includes some 'first fossil finds' which are recorded here. Several are of species known from the Recent of the Australian or Indo-West-Pacific regions, but some represent genera with a much wider temporal and geographical range. Of the 11 species illustrated, six are known, or may be inferred, to have inhabited 'sand fauna' environments. Specimens of one species are complete enough to allow its formal description as Chlidoniopsis inopina sp. nov.

Comparative aspects of natriuretic peptide physiology in non-mammalian vertebrates: a review

The natriuretic peptide system is a complex family of peptides and receptors that is primarily linked to the maintenance of osmotic and cardiovascular homeostasis. A natriuretic peptide system is present in each vertebrate class but there are varying degrees of complexity in the system. In agnathans and chondrichthyians, only one natriuretic peptide has been identified, while new data has revealed that multiple types of natriuretic peptides are present in bony fish. However, it seems in tetrapods that there has been a reduction in the number of natriuretic peptide genes, such that only three natriuretic peptides are present in mammals. The peptides act via a family of guanylyl cyclase receptors to generate the second messenger cGMP, which  mediates a range of physiological effects at key targets such as the gills, kidney and the cardiovascular system. This review summarises the current knowledge of the natriuretic peptide system in non-mammalian vertebrates and discusses the physiological actions of the peptides.

Solar versus fossil fuels : A net energy analysis of domestic solar hot water systems in Australia

It is commonly assumed that solar hot water systems save energy and reduce greenhouse gas emissions compared to conventional electric and gas hot water systems. Very rarely has the life-cycle energy requirements (including the embodied energy of manufacture) of solar hot water systems been analysed. The extent to which solar hot water systems can save energy compared to conventional electric or gas hot water systems can be shown through a comparative net energy analysis. This method determines the ‘energy payback period’, including consideration of the difference in operational energy savings and energy embodied in the devices relative to a base case. Dr Robert Crawford, Deakin University, Australia presents the results of a net energy analysis that compared solar and conventional hot water systems for a southern (Melbourne) and a northern (Brisbane) Australian climate.

Attitudes and knowledge of shade-coffee farmers towards vertebrates and their ecological functions.

The purpose of this study was to assess farmers’ attitudes, as well as perceptions and knowledge that shape those attitudes, toward the ecological role of vertebrates inhabiting shaded-coffee farms. We also aimed to determine whether differences existed among two groups of farmers: one that had attended environmental education workshops, and one that had not. We conducted 36 oral interviews of farmers in the region of Cuetzalan, Mexico. All farmers were members of an important regional cooperative, Tosepan Titataniske. In general, farmers’ attitudes towards birds were positive. Snakes were perceived as useful but dangerous animals. Attitudes towards nonflying mammals were mostly indifferent. Bats were poorly understood and badly perceived. Seed dispersal was perceived as an important ecological function performed by animals. Pollination was also perceived as important, but to a lesser degree. Knowledge about ecological functions was high for seed dispersal, and low for pollination. We found a positive correlation between attendance of educational workshops and the presence of “environmentally-friendly” attitudes, perceptions, and knowledge. However, a cause-effect relationship could not be clearly established. We suggest that environmental education programs include the objective of increasing the knowledge of people about the ecological functions played by different groups of animals that live in agroecosystems. Particular efforts should be directed toward improving the way in which certain non-charismatic groups of animals, such as bats, are perceived.

Chemical coding of vascular nitrergic nerves in lower vertebrates

Nitric oxide is an important regulator of blood pressure in mammals. This study provided new information on the role of nitric-oxide releasing sympathetic nerves in vascular regulation of lower vertebrates. The research outcomes advance knowledge on the potential role of these unique nerves in the control of the lower vertebrate cardiovascular system.

Mid-Holocene vertebrate bone Concentration-Lagerstätte on oceanic island Mauritius provides a window into the ecosystem of the dodo (Raphus cucullatus)

Although the recent history of human colonisation and impact on Mauritius is well documented, virtually no records of the pre-human native ecosystem exist, making it difficult to assess the magnitude of the changes brought about by human settlement. Here, we describe a 4000-year-old fossil bed at Mare aux Songes (MAS) in south-eastern Mauritius that contains both macrofossils (vertebrate fauna, gastropods, insects and flora) and microfossils (diatoms, pollen, spores and phytoliths). With >250 bone fragments/m2 and comprising 50% of all known extinct and extant vertebrate species (ns = 44) of Mauritius, MAS may constitute the first Holocene vertebrate bone Concentration-Lagerstätte identified on an oceanic volcanic island. Fossil remains are dominated by extinct giant tortoises Cylindraspis spp. (63%), passerines (10%), small bats (7.8%) and dodo Raphus cucullatus (7.1%). Twelve radiocarbon ages [four of them duplicates] from bones and other material suggest that accumulation of fossils took place within several centuries. An exceptional combination of abiotic conditions led to preservation of bones, bone collagen, plant tissue and microfossils. Although bone collagen is well preserved, DNA from dodo and other Mauritian vertebrates has proved difficult. Our analysis suggests that from ca 4000 years ago (4 ka), rising sea levels created a freshwater lake at MAS, generating an oasis in an otherwise dry environment which attracted a diverse vertebrate fauna. Subsequent aridification in the south-west Indian Ocean region may have increased carcass accumulation during droughts, contributing to the exceptionally high fossil concentration. The abundance of floral and faunal remains in this Lagerstätte offers a unique opportunity to reconstruct a pre-human ecosystem on an oceanic island, providing a key foundation for assessing the vulnerability of island ecosystems to human impact.

Investigation of GMP signalling systems in lower vertebrates

This research examined aspects of the cyclic GMP signalling system in fish and amphibians. It contributed new knowledge to our understanding of the role of the system in the development of zebrafish, a model fish species, and in control of the vasculature by the regulatory molecule, nitric oxide.

Vector activity and propagule size affect dispersal potential by vertebrates

Many small organisms in various life stages can be transported in the digestive system of larger vertebrates, a process known as endozoochory. Potential dispersal distances of these “propagules” are generally calculated after monitoring retrieval in experiments with resting vector animals. We argue that vectors in natural situations will be actively moving during effective transport rather than resting. We here test for the first time how physical activity of a vector animal might affect its dispersal efficiency. We compared digestive characteristics between swimming, wading (i.e. resting in water) and isolation (i.e. resting in a cage) mallards (Anas platyrhynchos). We fed plastic markers and aquatic gastropods, and monitored retrieval and survival of these propagules in the droppings over 24 h. Over a period of 5 h of swimming, mallards excreted 1.5 times more markers than when wading and 2.3 times more markers than isolation birds, the pattern being reversed over the subsequent period of monitoring where all birds were resting. Retention times of markers were shortened for approximately 1 h for swimming, and 0.5 h for wading birds. Shorter retention times imply higher survival of propagules at increased vector activity. However, digestive intensity measured directly by retrieval of snail shells was not a straightforward function of level of activity. Increased marker size had a negative effect on discharge rate. Our experiment indicates that previous estimates of propagule dispersal distances based on resting animals are overestimated, while propagule survival seems underestimated. These findings have implications for the dispersal of invasive species, meta-population structures and long distance colonization events.

RNA interference : more than a research tool in the vertebrates' adaptive immunity

In recent years, RNA silencing, usage of small double stranded RNAs of ~21 – 25 base pairs to regulate gene expression, has emerged as a powerful research tool to dissect the role of unknown host cell factors in this 'post-genomic' era. While the molecular mechanism of RNA silencing has not been precisely defined, the revelation that small RNA molecules are equipped with this regulatory function has transformed our thinking on the role of RNA in many facets of biology, illustrating the complexity and the dynamic interplay of cellular regulation. As plants and invertebrates lack the protein-based adaptive immunity that are found in jawed vertebrates, the ability of RNA silencing to shut down gene expression in a sequence-specific manner offers an explanation of how these organisms counteract pathogen invasions into host cells. It has been proposed that this type of RNA-mediated defence mechanism is an ancient form of immunity to offset the transgene-, transposon- and virus-mediated attack. However, whether 1) RNA silencing is a natural immune response in vertebrates to suppress pathogen invasion; or 2) vertebrate cells have evolved to counteract invasion in a 'RNA silencing' independent manner remains to be determined. A number of recent reports have provided tantalizing clues to support the view that RNA silencing functions as a physiological response to regulate viral infection in vertebrate cells. Amongst these, two manuscripts that are published in recent issues of Science and Immunity, respectively, have provided some of the first direct evidences that RNA silencing is an important component of antiviral defence in vertebrate cells. In addition to demonstrating RNA silencing to be critical to vertebrate innate immunity, these studies also highlight the potential of utilising virus-infection systems as models to refine our understanding on the molecular determinants of RNA silencing in vertebrate cells.