Detection of humpback whale (Megaptera novaeangliae) non-song vocalizations around the Vema Seamount, southeast Atlantic Ocean.

Humpback whales are a cosmopolitan, highly vocal species. Investigated here are their vocalizations recorded at the Vema Seamount (31°38'S, 08°20'E) from moored hydrophones in the austral spring of 2019. During the 11-d recording period over 600 non-song calls were detected. Calls were predominantly detected at night over three consecutive days. The most common calls were low, frequency-modulated sounds (whups). An impulsive sound (gunshot) previously unknown in humpback whales was also detected. The location and timing of the calls suggests that humpback whales may be using the Vema Seamount as a temporary stop on their migration to their polar feeding grounds.

Ocean-wide genomic variation in Gray's beaked whales, Mesoplodon grayi.

The deep oceans of the Southern Hemisphere are home to several elusive and poorly studied marine megafauna. In the absence of robust observational data for these species, genetic data can aid inferences on population connectivity, demography and ecology. A previous investigation of genetic diversity and population structure in Gray's beaked whale (Mesoplodon grayi) from Western Australia and New Zealand found high levels of mtDNA diversity, no geographic structure and stable demographic history. To further investigate phylogeographic and demographic patterns across their range, we generated complete mitochondrial and partial nuclear genomes of 16 of the individuals previously analysed and included additional samples from South Africa (n = 2) and South Australia (n = 4), greatly expanding the spatial range of genomic data for the species. Gray's beaked whales are highly elusive and rarely observed, and our data represents a unique and geographically broad dataset. We find relatively high levels of diversity in the mitochondrial genome, despite an absence of population structure at the mitochondrial and nuclear level. Demographic analyses suggest these whales existed at stable levels over at least the past 1.1 million years, with an approximately twofold increase in female effective population size approximately 250 thousand years ago, coinciding with a period of increased Southern Ocean productivity, sea surface temperature and a potential expansion of suitable habitat. Our results suggest that Gray's beaked whales are likely to be resilient to near-future ecosystem changes, facilitating their conservation. Our study demonstrates the utility of low-effort shotgun sequencing in providing ecological information on highly elusive species.

Bucking the trend: genetic analysis reveals high diversity, large population size and low differentiation in a deep ocean cetacean.

Understanding the genetic structure of a population is essential to its conservation and management. We report the level of genetic diversity and determine the population structure of a cryptic deep ocean cetacean, the Gray's beaked whale (Mesoplodon grayi). We analysed 530 bp of mitochondrial control region and 12 microsatellite loci from 94 individuals stranded around New Zealand and Australia. The samples cover a large area of the species distribution (~6000 km) and were collected over a 22-year period. We show high genetic diversity (h=0.933-0.987, π=0.763-0.996% and Rs=4.22-4.37, He=0.624-0.675), and, in contrast to other cetaceans, we found a complete lack of genetic structure in both maternally and biparentally inherited markers. The oceanic habitats around New Zealand are diverse with extremely deep waters, seamounts and submarine canyons that are suitable for Gray's beaked whales and their prey. We propose that the abundance of this rich habitat has promoted genetic homogeneity in this species. Furthermore, it has been suggested that the lack of beaked whale sightings is the result of their low abundance, but this is in contrast to our estimates of female effective population size based on mitochondrial data. In conclusion, the high diversity and lack of genetic structure can be explained by a historically large population size, in combination with no known exploitation, few apparent behavioural barriers and abundant habitat.

Plasmon-enhanced photocathode for high brightness and high repetition rate x-ray sources.

In this Letter, we report on the efficient generation of electrons from metals using multiphoton photoemission by use of nanostructured plasmonic surfaces to trap, localize, and enhance optical fields. The plasmonic surface increases absorption over normal metals by more than an order of magnitude, and due to the localization of fields, this results in over 6 orders of magnitude increase in effective nonlinear quantum yield. We demonstrate that the achieved quantum yield is high enough for use in rf photoinjectors operating as electron sources for MHz repetition rate x-ray free electron lasers.

Plasmon resonance tuning in metallic nanocavities.

Nanocavities fabricated in a metallic surface have important and technologically useful properties of complete light absorption and strong field enhancement. Here, we demonstrate how a nanometerthick alumina deposition inside such a cavity can be used to gain an exquisite control over the resonance wavelength. This process allows achieving a precise control over the spectral response and is completely reversible allowing many tuning attempts to be made on a single structure until the optimum performance is achieved.

Survey of plasma and liver mineral concentrations and enzyme activities in ostriches (Struthio camelus) under farmed conditions in New Zealand.

AIM: To generate clinical biochemical data to aid diagnosis of suboptimal performance in ostriches farmed under pastoral systems in New Zealand. METHODS: Blood and liver samples were sought from three categories of bird, viz 3-12-week-old chicks, 7-12-month-old growers, and from breeding hens, managed under pastoral conditions on farms in several locations in New Zealand. Concentrations of the minerals Ca, PO4, Mg, Na, K, Cu and Zn, activities of the enzymes gamma-glutamyl transferase (GGT), creatine kinase (CK), lactate dehydrogenase (LDH) and aspartate aminotransferase (AST), and concentrations of total protein (TP) and uric acid and vitamin E in plasma and Se in whole blood were determined from four flocks of chicks, two flocks of growing and one flock of breeding birds. Concentrations of Cu, Fe and vitamin B12 were determined from liver samples from chicks and growing birds. Bodyweight was recorded at the times of blood-sampling, where this was feasible. RESULTS: It proved impossible to obtain blood samples by venepuncture of the radial vein from chicks <3 months of age. Plasma concentrations of minerals, with the exception of K, which were higher, were within the normal range observed in the literature for ratite species. Activities in plasma of AST and CK were almost double, and those of LDH similar, to those in the literature for ostriches. There was considerable variation in activities of the enzymes between farms, but no association with growth performance. Concentrations of Cu in plasma were lower and in liver were higher than would be expected in farmed ruminants. Though hindgut fermenters, the birds maintained concentrations of vitamin B12 in plasma and liver at least comparable to those observed in ruminants. CONCLUSIONS: Collection of blood samples by venepuncture via the wing in ostrich chicks younger than 3 months of age is difficult and unlikely to prove viable for routine diagnostic purposes. Clinical biochemistry data on mineral nutrients in ostriches farmed in New Zealand are similar to those in the literature from South Africa , but AST and CK are higher, and may be normal and a reflection of the high growth rates of the musculoskeletal system.

Conformations of model peptides in membrane-mimetic environments.

The influence of a membrane environment on the conformational energetics of a polypeptide chain has been investigated through studies of model peptides in a variety of membrane-mimetic media. Nuclear magnetic resonance (NMR) and circular dichroism (CD) data have been obtained for the peptides in bulk hydrophobic solvents, normal micelles, and reversed micelles. Several hydrophobic peptides which are sparingly soluble in water have been solubilized in aqueous sodium dodecyl sulfate (SDS) solution. NMR and CD data indicate that the micelle-solubilized peptides experience an environment with the conformational impact of bulk methanol, and have decreased conformational freedom. The site of residence of the peptides interacting with the micelles appears to be near the surfactant head groups, in a region permeated by water, and not in the micelle core. Strongly hydrophilic peptides have been solubilized in nonpolar solvents by reversed micelles. These peptides are located in small water pools in close association with the head groups of the surfactant. NMR and CD data show that there is a conformational impact of this interfacial water region on peptide solubilizates distinct from that of bulk water.