Killer whales are capable of vocal learning

The production learning of vocalizations by manipulation of the sound production organs to alter the physical structure of sound has been demonstrated in only a few mammals. In this natural experiment, we document the vocal behaviour of two juvenile killer whales, Orcinus orca, separated from their natal pods, which are the only cases of dispersal seen during the three decades of observation of their populations. We find mimicry of California sea lion (Zalophus californianus) barks, demonstrating the vocal production learning ability for one of the calves. We also find differences in call usage (compared to the natal pod) that may reflect the absence of a repertoire model from tutors or some unknown effect related to isolation or context.     

Rapid Parallel Adaptation to Anthropogenic Heavy Metal Pollution

The impact of human-mediated environmental change on the evolutionary trajectories of wild organisms is poorly understood. In particular, capacity of species to adapt rapidly (in hundreds of generations or less), reproducibly and predictably to extreme environmental change is unclear. Silene uniflora is predominantly a coastal species, but it has also colonized isolated, disused mines with phytotoxic, zinc-contaminated soils. To test whether rapid, parallel adaptation to anthropogenic pollution has taken place, we used reduced representation sequencing (ddRAD) to reconstruct the evolutionary history of geographically proximate mine and coastal population pairs and found largely independent colonization of mines from different coastal sites. Furthermore, our results show that parallel evolution of zinc tolerance has occurred without gene flow spreading adaptive alleles between mine populations. In genomic regions where signatures of selection were detected across multiple mine-coast pairs, we identified genes with functions linked to physiological differences between the putative ecotypes, although genetic differentiation at specific loci is only partially shared between mine populations. Our results are consistent with a complex, polygenic genetic architecture underpinning rapid adaptation. This shows that even under a scenario of strong selection and rapid adaptation, evolutionary responses to human activities (and other environmental challenges) may be idiosyncratic at the genetic level and, therefore, difficult to predict from genomic data.     

Anterior Cervical Discectomy with Arthroplasty versus Arthrodesis for Single-Level Cervical Spondylosis: A Systematic Review and Meta-Analysis

Objective

To estimate the effectiveness of anterior cervical discectomy with arthroplasty (ACDA) compared to anterior cervical discectomy with fusion (ACDF) for patient-important outcomes for single-level cervical spondylosis.

Data sources

Electronic databases (MEDLINE, EMBASE, Cochrane Register for Randomized Controlled Trials, BIOSIS and LILACS), archives of spine meetings and bibliographies of relevant articles.

Study selection

We included RCTs of ACDF versus ACDA in adult patients with single-level cervical spondylosis reporting at least one of the following outcomes: functionality, neurological success, neck pain, arm pain, quality of life, surgery for adjacent level degeneration (ALD), reoperation and dysphonia/dysphagia. We used no language restrictions. We performed title and abstract screening and full text screening independently and in duplicate.

Data synthesis

We used random-effects model to pool data using mean difference (MD) for continuous outcomes and relative risk (RR) for dichotomous outcomes. We used GRADE to evaluate the quality of evidence for each outcome.

Results

Of 2804 citations, 9 articles reporting on 9 trials (1778 participants) were eligible. ACDA is associated with a clinically significant lower incidence of neurologic failure (RR  = 0.53, 95% CI  = 0.37–0.75, p = 0.0004) and improvement in the Neck pain visual analogue scale (VAS) (MD  = 6.56, 95% CI  = 3.22–9.90, p = 0.0001; Minimal clinically important difference (MCID)  = 2.5. ACDA is associated with a statistically but not clinically significant improvement in Arm pain VAS and SF-36 physical component summary. ACDA is associated with non-statistically significant higher improvement in the Neck Disability Index Score and lower incidence of ALD requiring surgery, reoperation, and dysphagia/dysphonia.

Conclusions

There is no strong evidence to support the routine use of ACDA over ACDF in single-level cervical spondylosis. Current trials lack long-term data required to assess safety as well as surgery for ALD. We suggest that ACDA in patients with single level cervical spondylosis is an option although its benefits and indication over ACDF remain in question.     

Demographic analysis of insect reproductive levels, patterns and heterogeneity: case study of laboratory strains of three Hawaiian tephritids

Reproductive data were collected on individually-held adult oriental fruit flies, Dacus dorsalis, melon flies, Dacus cucurbitae, and Mediterranean fruit flies, Ceratitis capitata including age-by-parity relations, birth interval, frequency distribution of individual egg production levels and the concentration of reproduction among females in a cohort. Specific findings include: i) delay in reproductive peaks in a cohort after eclosion is due almost entirely to the variance in attainment of reproductive maturity among individuals; ii) low reproductive output of reproductively mature melon flies is due mostly to long birth intervals; iii) high egg production in both the medfly and the oriental fruit fly is due to their consistency of egg laying levels and frequency (short birth intervals). Discussion stresses the importance of viewing reproduction, not as a singular and discrete life history trait, but as consisting of subcomponents of daily parity, cumulative parity and birth interval.

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Résumé Les informations sur la reproduction ont été obtenues à partir d'adultes de Dacus dorsalis, D. cucurbitae, C. capitata, élevés individuellement. Elles portent sur les paramètres suivants: distribution par âge en fonction de la fécondité, échelonnement des pontes, distribution des niveaux quotidiens de ponte, fréquence des pondeuses par cohorte.Différents caractères spécifiques ont été mis en évidence: 1) La variabilité de la date d'apparition de la maturité reproductive est pour l'essentiel responsable du retard dans les dates de reproduction maximale; 2) De 30 à 50% des femelles de D. dorsalis âgées de 10 jours pondent plus de 50 oeufs/jour pendant les deux semaines qui suivent, tandis que seulement 10 à 20% des femelles des deux autres espèces parviennent à pondre cette quantité d'oeufs à n'importe quel âge; 3) D. cucurbitae ayant atteint sa maturité pond environ pendant 40% des jours (c.à.d. chaque 2,5 j), tandis que les deux autres espèces pondent au moins quelques oeufs pendant 80% des jours (c.à.d. chaque 1,25 j); 4) La production élevée d'oeufs de C. capitata et de D. dorsalis est due à la régularité de leur niveau de ponte et à la fréquence (faible espacement); 5) Les fractions des effectifs qui ont pondu au moins 600 oeufs en 30 jours étaient approximativement de 0,8, 0,7, et 0,4 pour D. dorsalis, C. capitata, D. cucurbitae; 6) 50% des femelles de chacune des trois espèces contribuent en gros pour 65% à la ponte.

     

Eosinophils preferentially use bromide to generate halogenating agents

Human eosinophils preferentially utilize bromide to generate a brominating agent, even at physiological halide concentrations, where chloride (140 mM) is over 1000-fold greater than bromide (20-100 microM). Under the same conditions, neutrophils use chloride to generate a chlorinating agent. The total amount of active halogen trapped by 1,3,5-trimethoxybenzene from eosinophils increases by over 2-fold as the added bromide concentration increases from 0 to 100 microM, with approximately 40 nmol of halogen trapped per million cells at the highest bromide level. At least 25-35% of the oxygen consumed by stimulated eosinophils is directed toward the generation of halogenating species. Since the relative halogenating behavior of eosinophil peroxidase and neutrophil myeloperoxidase in this bromide range is essentially identical to that of the cells, the specificity of eosinophils toward bromide is intrinsic to eosinophil peroxidase and not to any special cellular properties. These results suggest that human eosinophils use bromide in vivo and that a deficiency of bromide may influence their ability to produce halogenating agents.     

An approach to the use of stable isotopes for DNA sequencing

The sequencing of DNA by current procedures involves the use of radioisotopic or fluorescent labels. We propose that stable isotopes can be used as such labels and that the large number of stable isotopes available would allow multiplexing so that many DNA segments could be sequenced simultaneously. We have developed methods to use 57Fe2O3 to synthesize ferrocene and to attach the ferrocene to the 5' end of oligonucleotides. The 57Fe-labeled M13 universal primer functioned normally in a Sanger sequencing procedure. When a 57Fe-labeled oligonucleotide had migrated on a polyacrylamide gel it was readily located on the dried gel by scanning with resonance ionization spectroscopy (RIS) coupled with mass spectrometry. Using a 57Fe-labeled primer in a PCR reaction a 2000-bp DNA was produced that was detected by RIS on nylon membrane after agarose electrophoresis. The rapid analysis features of RIS coupled with the multispectral multiplexing possibilities of stable isotopes should significantly increase the rate of determination of DNA sequences.     

Are rice chromosomes components of a holocentric chromosome ancestor?

Comparative genomics reveals that cereal genomes are composed of similar genomic building blocks (linkage blocks). By stacking these blocks in a unique order, it is possible to construct a single ancestral chromosome which can be cleaved to give the basic structure of the 56 different chromosomes found in wheat, rice, maize, sorghum, millet and sugarcane. The borders of linkage blocks are defined by cereal centromeric and telomeric sites. However, a number of studies have shown that telomeric heterochromatin has neocentromeric activity, implying that linkage blocks are in fact defined by centromeric-like sites with conserved sequences. The structure of the ancestral cereal genome thus resembles a holocentric chromosome, which is the chromosome structure shared by the closest relatives of the Gramineae, the Cypericeae and Juncaceae.