Can a seed bank provide demographic and genetic rescue in a declining population of the endangered shrub <Emphasis Type="Italic">Acacia pinguifolia</Emphasis>?

Many threatened species suffer reduced genetic diversity as a result of small population size and isolation. However, species with a persistent seed bank may be buffered against genetic loss as seed banks are expected to accumulate the reproductive output of many seasons. For fire-dependent species in decline, prescribed ecological burning may be a means to stimulate germination and recover genetic diversity stored in the seed bank, providing a demographic and genetic rescue effect. Here we investigated the effectiveness of this strategy in a small, isolated and inbred population of the endangered shrub, Acacia pinguifolia. We surveyed genetic diversity and structure of remnant populations of A. pinguifolia and monitored regeneration before and after burning. Germination was stimulated by fire, but seedling numbers 18 months post-fire were low and barely above the number of adults killed by the fire. Genetic diversity was marginally higher in the post-fire seedling cohort than the pre-fire adults (H_E = 0.1 vs. 0.09, respectively). Outcrossing rates of open-pollinated seed from surrounding plants suggested moderately high levels of self-fertilisation (t _m  = 0.65) and analysis of fine-scale genetic structure implied pollen and seed dispersal over distances of several metres, suggesting that restricted gene flow and inbreeding may act to limit genetic diversity in the seed bank. We conclude that prescribed burning has not been immediately successful as a recovery strategy for this relictual population of A. pinguifolia, though future monitoring may detect additional recruits. Alternative conservation strategies, including performing inter-population crosses, may be required to restore genetic diversity and ameliorate extinction risks.     

Specific combination of compound heterozygous mutations in 17β-hydroxysteroid dehydrogenase type 4 (<Emphasis Type="Italic">HSD17B4</Emphasis>) defines a new subtype of D-bifunctional protein deficiency

Background

D-bifunctional protein (DBP) deficiency is typically apparent within the first month of life with most infants demonstrating hypotonia, psychomotor delay and seizures. Few children survive beyond two years of age. Among patients with prolonged survival all demonstrate severe gross motor delay, absent language development, and severe hearing and visual impairment. DBP contains three catalytically active domains; an N-terminal dehydrogenase, a central hydratase and a C-terminal sterol carrier protein-2-like domain. Three subtypes of the disease are identified based upon the domain affected; DBP type I results from a combined deficiency of dehydrogenase and hydratase activity; DBP type II from isolated hydratase deficiency and DBP type III from isolated dehydrogenase deficiency. Here we report two brothers (16½ and 14 years old) with DBP deficiency characterized by normal early childhood followed by sensorineural hearing loss, progressive cerebellar and sensory ataxia and subclinical retinitis pigmentosa.

Methods and results

Biochemical analysis revealed normal levels of plasma VLCFA, phytanic acid and pristanic acid, and normal bile acids in urine; based on these results no diagnosis was made. Exome analysis was performed using the Agilent SureSelect 50Mb All Exon Kit and the Illumina HiSeq 2000 next-generation-sequencing (NGS) platform. Compound heterozygous mutations were identified by exome sequencing and confirmed by Sanger sequencing within the dehydrogenase domain (c.101C>T; p.Ala34Val) and hydratase domain (c.1547T>C; p.Ile516Thr) of the 17β-hydroxysteroid dehydrogenase type 4 gene (HSD17B4). These mutations have been previously reported in patients with severe-forms of DBP deficiency, however each mutation was reported in combination with another mutation affecting the same domain. Subsequent studies in fibroblasts revealed normal VLCFA levels, normal C26:0 but reduced pristanic acid beta-oxidation activity. Both DBP hydratase and dehydrogenase activity were markedly decreased but detectable.

Conclusions

We propose that the DBP phenotype seen in this family represents a distinct and novel subtype of DBP deficiency, which we have termed type IV based on the presence of a missense mutation in each of the domains of DBP resulting in markedly reduced but detectable hydratase and dehydrogenase activity of DBP. Given that the biochemical testing in plasma was normal in these patients, this is likely an underdiagnosed form of DBP deficiency.

     

When Giants Turn Up: Sighting Trends,Environmental Influences and Habitat Use of the Manta Ray Manta alfredi at a Coral Reef

Manta rays Manta alfredi are present all year round at Lady Elliot Island (LEI) in the southern Great Barrier Reef, Australia, with peaks in abundance during autumn and winter. Drivers influencing these fluctuations in abundance of M. alfredi at the site remain uncertain. Based on daily count, behavioural, weather and oceanographic data collected over a three-year period, this study examined the link between the relative number of sightings of manta rays at LEI, the biophysical environment, and the habitat use of individuals around the LEI reef using generalised additive models. The response variable in each of the three generalised additive models was number of sightings (per trip at sea) of cruising, cleaning or foraging M. alfredi. We used a set of eleven temporal, meteorological, biological, oceanographic and lunar predictor variables. Results for cruising, cleaning and foraging M. alfredi explained 27.5%, 32.8% and 36.3% of the deviance observed in the respective models and highlighted five predictors (year, day of year, wind speed, chlorophyll-a concentration and fraction of moon illuminated) as common influences to the three models. There were more manta rays at LEI in autumn and winter, slower wind speeds, higher productivity, and around the new and full moon. The winter peak in sightings of foraging M. alfredi was found to precede peaks in cleaning and cruising activity around the LEI reef, which suggests that enhanced food availability may be a principal driver for this seasonal aggregation. A spatial analysis of behavioural observations highlighted several sites around the LEI reef as ‘multi-purpose’ areas where cleaning and foraging activities commonly occur, while the southern end of the reef is primarily a foraging area. The use of extensive citizen science datasets, such as those collected by dive operators in this study, is encouraged as they can provide valuable insights into a species'' ecology.     

VAMP1 Mutation Causes Dominant Hereditary Spastic Ataxia in Newfoundland Families

Our group previously described and mapped to chromosomal region 12p13 a form of dominantly inherited hereditary spastic ataxia (HSA) in three large Newfoundland (Canada) families. This report identifies vesicle-associated membrane protein 1 (VAMP1), which encodes a critical protein for synaptic exocytosis, as the responsible gene. In total, 50 affected individuals from these families and three independent probands from Ontario (Canada) share the disease phenotype together with a disruptive VAMP1 mutation that affects a critical donor site for the splicing of VAMP1 isoforms. This mutation leads to the loss of the only VAMP1 isoform (VAMP1A) expressed in the nervous system, thus highlighting an association between the well-studied VAMP1 and a neurological disorder. Given the variable phenotype seen in the affected individuals examined here, we believe that VAMP1 should be tested for mutations in patients with either ataxia or spastic paraplegia.     

Expression,purification, crystallization,and preliminary X-ray analysis of recombinant human saposin B

Saposin B (also known as cerebroside sulfate activator or CSAct) is a small non-enzymatic glycoprotein required for the breakdown of cerebroside sulfates (sulfatides) in lysosomes. Saposin B contains three intramolecular disulfide bridges, exists as a dimer and is remarkably heat, protease, and pH stable. We have expressed the protein in a thioredoxin reductase deficient strain of Escherichia coli and purified the protein by heat treatment, followed by ion-exchange, gel filtration, and hydrophobic interaction chromatographies. The protein is properly folded as judged by the observed disulfide bond topology, the hydrogen-deuterium exchange rate, and the level of stimulation of sulfatide hydrolysis by arylsulfatase A. Crystals of human saposin B were grown by vapor diffusion and diffract to a resolution of 2.2A. Despite obtaining only merohedrally twinned P3(1) native crystals, an untwined seleomethionine-substituted crystal belonging to space group P3(1)21 was also grown. The three-dimensional structure of saposin B protein will provide insights into how this 79 amino acid protein is able to solubilize relatively large membrane-bound lipid ligands.     

Temporal changes in the prevalence of parasites in two Oregon estuary-dwelling fishes

The parasite faunas of juvenile English sole (Parophrys vetulus) in 1971-1972 and staghorn sculpin (Leptocottus armatus) in 1971 from Yaquina Bay, Oregon, were compared with faunas found in the same estuary in 1997-2000 (English sole) and 1999-2000 (staghorn sculpin). The 7 most commonly occurring parasites in 1971 were compared with the same species observed during the same month and sampling sites in 1997-2000. Multivariate community analysis of juvenile English sole parasites supported the suggestion that the 1971 parasite data were representative of the early-1970s time period. Four of the parasite species infecting English sole and 6 of those infecting staghorn sculpins had significantly lower prevalences in 1997-2000. Parasite species with significantly lower prevalences also had reduced intensity levels. One parasite (Glugea stephani) of English sole increased in prevalence in the 1997-2000 samples in association with the warm estuarine temperatures during the 1997 El Ni?o year. Although the causes for the changes in occurrence of other parasites were not determined, ecological changes in Yaquina Bay that may have influenced parasite ecology include apparent changes in the estuary ichthyofauna that occurred between the sampling periods. Such changes could be associated with increases in the number of California sea lions (Zalophus californianus) subsequent to establishment of the Marine Mammal Protection Act in 1972.     

Synthesis and biological evaluation of novel, selective, nonsteroidal glucocorticoid receptor antagonists

We report the discovery of a novel class of glucocorticoid receptor (GR) antagonists based on the chromene molecular scaffold. The compounds exhibit good functional potency and an improved receptor selectivity profile for GR over other steroid receptors when compared to the classical steroidal GR-antagonist, RU-486.     

Synthesis and evaluation of 2-amino-8-alkoxy quinolines as MCHr1 antagonists. Part 1

A high-throughput screen was performed in order to identify chemotypes that are bound by the melanin concentrating hormone receptor-1 (MCHr1). A novel 2-amino-8-alkoxyquinoline compound (1) was identified and subsequently optimized using a parallel and automated procedure for the rapid production of multiple analogs. The structure-activity relationships that emerged from this effort are described, along with selected pharmacokinetic parameters of compound (d)-61 when dosed orally in diet-induced obese mice.     

Inhibition kinetics of carba- and C-fucosyl analogues of GDP-fucose against fucosyltransferase V: implication for the reaction mechanism

Inhibition kinetics of two isosteric analogues of GDP-fucose (GDP-Fuc) were investigated against fucosyltransferase V using electrospray ionization mass spectrometry coupled to multiple reaction monitoring. The carba-Fuc analogue was found to be a competitive inhibitor with a K(i) value of 67.1+/-9.8 microM, similar to the K(m) value for GDP-Fuc (50.4+/-5.5 microM), while the C-Fuc analogue exhibited significantly weak competitive inhibition with a K(i) value of 889+/-93 microM.