Marine Biodiversity of Aotearoa New Zealand

The marine-biodiversity assessment of New Zealand (Aotearoa as known to Māori) is confined to the 200 nautical-mile boundary of the Exclusive Economic Zone, which, at 4.2 million km2, is one of the largest in the world. It spans 30° of latitude and includes a high diversity of seafloor relief, including a trench 10 km deep. Much of this region remains unexplored biologically, especially the 50% of the EEZ deeper than 2,000 m. Knowledge of the marine biota is based on more than 200 years of marine exploration in the region. The major oceanographic data repository is the National Institute of Water and Atmospheric Research (NIWA), which is involved in several Census of Marine Life field projects and is the location of the Southwestern Pacific Regional OBIS Node; NIWA is also data manager and custodian for fisheries research data owned by the Ministry of Fisheries. Related data sources cover alien species, environmental measures, and historical information. Museum collections in New Zealand hold more than 800,000 registered lots representing several million specimens. During the past decade, 220 taxonomic specialists (85 marine) from 18 countries have been engaged in a project to review New Zealand's entire biodiversity. The above-mentioned marine information sources, published literature, and reports were scrutinized to give the results summarized here for the first time (current to 2010), including data on endemism and invasive species. There are 17,135 living species in the EEZ. This diversity includes 4,315 known undescribed species in collections. Species diversity for the most intensively studied phylum-level taxa (Porifera, Cnidaria, Mollusca, Brachiopoda, Bryozoa, Kinorhyncha, Echinodermata, Chordata) is more or less equivalent to that in the ERMS (European Register of Marine Species) region, which is 5.5 times larger in area than the New Zealand EEZ. The implication is that, when all other New Zealand phyla are equally well studied, total marine diversity in the EEZ may be expected to equal that in the ERMS region. This equivalence invites testable hypotheses to explain it. There are 177 naturalized alien species in New Zealand coastal waters, mostly in ports and harbours. Marine-taxonomic expertise in New Zealand covers a broad number of taxa but is, proportionately, at or near its lowest level since the Second World War. Nevertheless, collections are well supported by funding and are continually added to. Threats and protection measures concerning New Zealand's marine biodiversity are commented on, along with potential and priorities for future research

Initial and final state effects in photoemission from Au nanoclusters on TiO2 (110)

Valence level and shallow core states of Au nanoclusters on TiO 2(1 1 0) have been studied by synchrotron excited photoemission. The shift to high binding energy and broadening of the Au4f peaks with decreasing Au surface coverage can be understood in terms of decreasing cluster size and the associated effects of charge on the cluster in the final state. Shifts in the photoemission onset are much more pronounced than the core level shifts and show a strong dependence on the degree of reduction of the TiO 2(1 1 0) substrate. These observations suggest that the photoemission onset is influenced by an initial state effect involving charge transfer from defect states into cluster states. © 2002 Elsevier Science B.V. All rights reserved

Gametogenic and reproductive cycles of the sea anemone, Entacmaea quadricolor

Host sea anemones are ecologically important as they provide habitat for obligate symbiotic anemonefish in many areas of the Indo-Pacific. Despite their importance, no information is available on their gametogenic cycles. This study aimed to address this lack of knowledge by determining the gametogenic cycles of Entacmaea quadricolor. Gonad samples were taken from January 2003 to February 2005 at North Solitary Island, Solitary Islands Marine Park, Australia using a specially developed non-lethal field biopsy sampling technique. Sampling was done 17 times during the study period, with 15–20 individuals being sampled on each occasion. Samples were examined prior to fixation, and then histologically sectioned to determine the reproductive activity of each individual. Female anemones were significantly more abundant than males, and had asynchronous oocyte development both within and among individuals. Male anemones showed a single annual cycle of spermary growth, development and spawning. Data from the 26-month study indicated that spawning occurred in the austral summer and autumn between January and April, which coincided with the observed spawning periods that have previously been documented for this species in outdoor flow-through seawater tanks at the study location. The biopsy sampling technique used during this study provides an opportunity to gain a more thorough understanding of the gametogenic cycles and sexual pattern of host sea anemones throughout their distribution

RGMa regulates cortical interneuron migration and differentiation

The etiology of neuropsychiatric disorders, including schizophrenia and autism, has been linked to a failure to establish the intricate neural network comprising excitatory pyramidal and inhibitory interneurons during neocortex development. A large proportion of cortical inhibitory interneurons originate in the medial ganglionic eminence (MGE) of the ventral telencephalon and then migrate through the ventral subventricular zone, across the corticostriatal junction, into the embryonic cortex. Successful navigation of newborn interneurons through the complex environment of the ventral telencephalon is governed by spatiotemporally restricted deployment of both chemorepulsive and chemoattractive guidance cues which work in concert to create a migratory corridor. Despite the expanding list of interneuron guidance cues, cues responsible for preventing interneurons from re-entering the ventricular zone of the ganglionic eminences have not been well characterized. Here we provide evidence that the chemorepulsive axon guidance cue, RGMa (Repulsive Guidance Molecule a), may fulfill this function. The ventricular zone restricted expression of RGMa in the ganglionic eminences and the presence of its receptor, Neogenin, in the ventricular zone and on newborn and maturing MGE-derived interneurons implicates RGMa-Neogenin interactions in interneuron differentiation and migration. Using an in vitro approach, we show that RGMa promotes interneuron differentiation by potentiating neurite outgrowth. In addition, using in vitro explant and migration assays, we provide evidence that RGMa is a repulsive guidance cue for newborn interneurons migrating out of the ganglionic eminence ventricular zone. Intriguingly, the alternative Neogenin ligand, Netrin-1, had no effect on migration. However, we observed complete abrogation of RGMa-induced chemorepulsion when newborn interneurons were simultaneously exposed to RGMa and Netrin-1 gradients, suggesting a novel mechanism for the tight regulation of RGMa-guided interneuron migration. We propose that during peak neurogenesis, repulsive RGMa-Neogenin interactions drive interneurons into the migratory corridor and prevent re-entry into the ventricular zone of the ganglionic eminences