Abalone I: Analyzing Mark-Recapture-Recovery Data Incorporating Growth and Delayed Recovery

Abalone are semimobile marine gastropods that form the basis of Australia's second most valuable fishery. A site off the coast of Port Arthur, Tasmania, was visited on six occasions. On each occasion, any unmarked live abalone found were marked with a unique identification number and were recorded. Any previously marked abalone found had its identification number and whether or not it was still alive recorded. This results in integrated mark-recapture-recovery data, as in Catchpole et al. (1998, Biometrics 54, 33-46). During the study period, abalone grew in size, and we model the survival of individuals as a function of their size, estimated from a fitted growth curve. The shells of dead animals are long lasting, and we extend existing methodology to allow for the possibility that an animal found dead may have been dead but overlooked for several visits.     

The nucleotide sequence of Staphylococcus aureus plasmid pT48 conferring inducible macrolide-lincosamide-streptogramin B resistance and comparison with similar plasmids expressing constitutive resistance

The complete nucleotide sequence of a naturally occurring Staphylococcus aureus plasmid, pT48 (from S. aureus strain T48), has been determined. The 2475 bp plasmid confers inducible resistance to macrolide-lincosamide-streptogramin B (MLS) type antibiotics. It is similar to the constitutive MLS resistance plasmid, pNE131, from Staphylococcus epidermidis and shows homology with S. aureus plasmids pSN2 and pE194. It contains a palA structure homologous to that on S. aureus plasmid pT181. The open reading frame, ORF B, within the pSN2 homologous region has a frameshifted C-terminus, relative to pNE131, resulting in a smaller, 158 amino acid putative polypeptide. The pE194 homologous region has the ermC resistance determinant and retains the leader region, deleted in pNE131, required for inducible expression of an adenine methylase. Another naturally occurring S. aureus strain, J74, shows constitutive resistance to erythromycin and contains a small plasmid, pJ74, which is similar to pNE131 but with a different deletion in the leader sequence. The results are consistent with the translational attenuation model for ermC expression.     

An Age-Associated Decline in Thymic Output Differs in Dog Breeds According to Their Longevity

The age associated decline in immune function is preceded in mammals by a reduction in thymic output. Furthermore, there is increasing evidence of a link between immune competence and lifespan. One approach to determining thymic output is to quantify signal joint T cell receptor excision circles (sj-TRECs), a method which has been developed and used in several mammalian species. Life expectancy and the rate of aging vary in dogs depending upon their breed. In this study, we quantified sj-TRECs in blood samples from dogs of selected breeds to determine whether there was a relationship between longevity and thymic output. In Labrador retrievers, a breed with a median expected lifespan of 11 years, there was an age-associated decline in sj-TREC values, with the greatest decline occurring before 5 years of age, but with sj-TREC still detectable in some geriatric animals, over 13 years of age. In large short-lived breeds (Burnese mountain dogs, Great Danes and Dogue de Bordeaux), the decline in sj-TREC values began earlier in life, compared with small long-lived breeds (Jack Russell terriers and Yorkshire terriers), and the presence of animals with undetectable sj-TRECs occurred at a younger age in the short-lived breeds. The study findings suggest that age-associated changes in canine sj-TRECs are related to breed differences in longevity, and this research highlights the use of dogs as a potential model of immunosenescence.     

Imaging Spatial Variations of Optical Bandgaps in Perovskite Solar Cells

A fast, nondestructive, camera‐based method to capture optical bandgap images of perovskite solar cells (PSCs) with micrometer‐scale spatial resolution is developed. This imaging technique utilizes well‐defined and relatively symmetrical band‐to‐band luminescence spectra emitted from perovskite materials, whose spectral peak locations coincide with absorption thresholds and thus represent their optical bandgaps. The technique is employed to capture relative variations in optical bandgaps across various PSCs, and to resolve optical bandgap inhomogeneity within the same device due to material degradation and impurities. Degradation and impurities are found to both cause optical bandgap shifts inside the materials. The results are confirmed with micro‐photoluminescence spectroscopy scans. The excellent agreement between the two techniques opens opportunities for this imaging concept to become a quantified, high spatial resolution, large‐area characterization tool of PSCs. This development continues to strengthen the high value of luminescence imaging for the research and development of this photovoltaic technology.     

Spatial distribution of discards in mixed fisheries: species trade-offs,potential spatial avoidance and national contrasts

Reviews in Fish Biology and Fisheries - Since 2015, the European Union gradually implemented the landing obligation (LO). This prohibits at-sea discarding of species under total allowable catch...     

Song and brain development in canaries raised under different conditions of acoustic and social isolation over two years

Early isolation experiments indicate that male songbirds learn their songs during an early sensitive period, although later work has shown that some open-ended learners modify songs in later years. Recent isolation experiments suggest that in some species song has a stronger genetic basis than previously thought. This study raised domestic canaries under different combinations of acoustic and social isolation and followed song development into the second year. Males raised alone in acoustic isolation developed songs with normal syllables, but larger repertoires and also produced syllables with lower repetition rates when compared to controls. The smallest repertoire occurred in males raised in a peer group. Isolate males had a smaller song control nucleus HVC than controls, but there was no effect on nucleus RA or on brain weight in general. In the second year, after introduction into a large normal colony, isolate and peer group males adjusted their syllable repertoire to normal size. In particular, the isolates reduced their repertoire even though the size of HVC showed a significant increase in volume. However, songs of isolate and peer group males still differ in repetition rate and number of single syllables in the common aviary. In contrast, control males showed low syllable turnover and no significant change in repertoire size. Nor did they show any significant change in the volumes of song control nuclei. It seems that complete isolation affects only some aspects of song and brain development, and later socialization corrects some but not all of these in the second year.     

Developmental stress, social rank and song complexity in the European starling (Sturnus vulgaris)

Bird song is a sexually selected trait and females have been shown to prefer males that sing more complex songs. However, for repertoire size to be an honest signal of male quality it must be associated with some form of cost. This experiment investigates the effects of food restriction and social status during development on song complexity in the European starling (Sturnus vulgaris). Birds that experienced an unpredictable food supply early in life produced a significantly smaller repertoire of song phrases than those with a constant food supply. Social status during development was also significantly correlated with repertoire size, with dominant birds producing more phrase types. This study therefore provides novel evidence that social as well as nutritional history may be important in shaping the song signal in this species.