POPULATION BIOLOGY OF THE TRANS-ARCTIC EXCHANGE: MtDNA SEQUENCE SIMILARITY BETWEEN PACIFIC AND ATLANTIC SEA URCHINS

MtDNAs from 2 protein coding regions comprising 576 base pairs were sequenced from 17 individual sea urchins of the species Strongylocentrotus pallidus collected from the north Pacific and north Atlantic oceans. Twelve of 17 individual sequences were identical. Two of these were further sequenced in a third, 441 base pair region, and were also found to be identical. We show how to interpret these results using a simplified Markov model of mtDNA evolution at silent sites. The model was calibrated using 3 urchin species with a published fossil record, and shows that identical S. pallidus mtDNAs in different oceans shared a common ancestor at most 90,000–150,000 years ago (95% confidence interval of upper limit of divergence). The Markov model, used to examine patterns of genetic distance within and between species, shows unexpected variation in the rate of base substitution. The rate of change of G's at fourfold sites is nearly 20 times greater than the rate of change of C's. At twofold sites, this range is less extreme, although purines consistently have a higher rate of change than pyrimidines. Striking genetic similarity and recent genetic exchange between oceans for these urchins is in marked contrast to most other trans-Arctic marine populations, which usually show morphological and genetic differentiation at the species or subspecies level. Recent fossil evidence shows that the north Atlantic and northeastern Pacific have been the scene of radical faunal changes during the Pliocene and Pleistocene. The genetic results presented here extend this conclusion to intraspecific patterns of genetic variability, and direct attention to the northwest Pacific where higher productivity and less environmental change may have left a heritage of greater marine genetic diversity.     

Postmortem Changes in Rat Brain Extracellular Opioid Peptides Revealed by Microdialysis

Microdialysis combined with a solid-phase radioimmunoassay was used to monitor changes in extracellular opioid peptide levels in the rat globus pallidus/ventral pallidum as a result of terminal brain ischemia. Ischemia was induced by anesthetic overdose or by severance of blood vessels supplying the brain. In control animals the recovered immunoreactivity increased an average of 13-fold in the 30-min sample following anesthetic overdose. Perfusion of a calcium-free, 10 mM EGTA-containing medium through the dialysis probe significantly attenuated the amplitude of this response, with the average increase being only threefold. Shorter sampling intervals (5 min) indicated that release of opioid peptide material into the extracellular environment occurs within the first 5 min of ischemia resulting from severance of the blood supply to the brain. HPLC analysis identified the majority of the postmortem-induced immunoreactive material as Met- and Leu-enkephalin.     

Microelectrode Neuronal Activity of the Internal Globus Pallidus in Dystonia Correlates with Postoperative Neuromodulation Effects and Placement of the Stimulation Electrode

BackgroundDeep brain stimulation (DBS) is emerging as a viable treatment option for selected patients with dystonia. Intraoperative extracellular microelectrode recordings (MER) are considered as the standard electrophysiological method for the precise positioning of the DBS electrode into the target brain structure. Accurate targeting of the permanent stimulation electrode into the Globus Pallidus internus (GPi) is key to positive long-term effects. The suitability of the location is peroperatively assessed by microelectrodes that register single-unit neuronal activity. The aim of this article is to analyse electrophysiological recordings of patient's neuronal activity with a focus on the identification of markers relevant to the patient's clinical state.MethodsIn this study, 13 patients chronically treated with double-sided DBS GPi were examined with a microrecording. The signal (24 kHz) processing, included bandpass filtering (0.5–5 kHz), automated detection of artefacts and feature extraction. Pre-processed signals were analysed by means of statistical learning.ResultsThe results show that the GPi was distinguished from its vicinity with p < 0.001 and 3 machine learning models AUCs had an accuracy of higher than 0.87. The observed biomarker, Hjort mobility, additionally correlated with the long-term neuromodulation effect (rho = −0.4; p < 0.05). Furthermore, we revealed a change of neural activity associated with the active distal DBS contact localization along the medio-lateral direction.ConclusionThis paper demonstrates the quantitative relationship between electrophysiological findings and the clinical effects of pallidal stimulation in dystonia and suggested objectification predictors of the effectiveness of this therapy.     

Climate anomalies affect annual survival rates of swifts wintering in sub‐Saharan Africa

Several species of migratory swifts breed in the Western Palearctic, but they differ in reproductive traits and nonbreeding areas explored in Africa. We examined survival and recapture probabilities of two species of swifts by capture–mark–recapture data collected in northern Italy (Pallid Swift Apus pallidus in Carmagnola, Turin, and Common Swift Apus apus in Guiglia, Modena) in the breeding season (May–July). Apparent survival rates were relatively high (>71%), comparable to other studies of European swifts, but showed marked annual variations. We used geolocators to establish the exact wintering areas of birds breeding in our study colonies. Common Swifts explored the Sahel zone during migration and spent the winter in SE Africa, while the Pallid Swifts remained in the Sahel zone for a longer time, shifting locations southeast down to Cameroun and Nigeria later in winter. These movements followed the seasonal rains from north to south (October to December). In both species, we found large yearly differences in survival probabilities related to different climatic indices. In the Pallid Swift, wintering in Western Africa, the Sahel rainfall index best explained survival, with driest seasons associated with reduced survival. In the Common Swift, wintering in SE Africa, the El Niño–Southern Oscillation (ENSO) cycle performed significantly better than Sahel rainfall or North Atlantic Oscillation (NAO). Extreme events and precipitation anomalies in Eastern Africa during La Niña events resulted in reduced survival probabilities in Common Swifts. Our study shows that the two species of swifts have similar average annual survival, but their survival varies between years and is strongly affected by different climatic drivers associated with their respective wintering areas. This finding could suggest important ecological diversification that should be taken into account when comparing survival and area use of similar species that migrate between temperate breeding areas and tropical wintering areas.     

Intracerebral quantitative chromophore estimation from reflectance spectra captured during deep brain stimulation implantation

Quantification of blood fraction (f_blood), blood oxygenation (S), melanin, lipofuscin and oxidised and reduced Cytochrome aa 3 and c was done from diffuse reflectance spectra captured in cortex, white matter, globus pallidus internus (GPi) and subthalamus during stereotactic implantations of 29 deep brain stimulation (DBS) electrodes with the aim of investigating whether the chromophores can give physiological information about the targets for DBS. Double‐sided Mann‐Whitney U ‐tests showed more lipofuscin in GPi compared to white matter and subthalamus (p < 0.05). Compared to the other structures, f_bloodwas significantly higher in cortex (p < 0.05) and S lower in GPi (p < 0.05). Median values and range for f_blood were 1.0 [0.2–6.0]% in the cortex, 0.3 [0.1–8.2]% in white matter, 0.2 [0.1–0.8]% in the GPi and 0.2 [0.1–11.7]% in the subthalamus. Corresponding values for S was 20 [0–81]% in the cortex, 29 [0–78]% in white matter, 0 [0–0]% in the GPi and 0 [0–92]% in the subthalamus. In conclusion, the measurements indicate very low oxygenation and blood volume for DBS patients, especially in the GPi. It would be of great interest to investigate whether this is due to the disease, the normal situation or an artefact of doing invasive measurements. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Is the Cape White-eye Zosterops virens or Zosterops capensis?

The recent scientific literature employs three binomial names for the southern African endemic bird known as the Cape White-eye: Zosterops capensis, Z. pallidus and Z. virens. This unacceptable inconsistency reflects the contention regarding white-eye systematics. Recent molecular work by Oatley and colleagues led to the suggestion that Z. virens and Z. capensis should both fall under the name Z. virens. We urge ornithologists to adopt this convention, and we encourage further molecular stud ies in order to clarify the taxonomy of southern African white-eyes.     

New species and new stage descriptions of Campsurus major species group (Polymitarcyidae: Campsurinae), with first report of silk-case construction in mayfly nymphs

Campsurus major, C. argentinus and C. amapaensis sp. nov. form a monophyletic group supported by the following apomorphies in the male genitalia: robust pedestals with a widely rounded inner-posterior margin and a more acute and thinner outer margin, penes strongly sclerotised and curved ventrally, each lobe twisted outwards, and with a small membranous lobe on ventral margin. The nymphs of Campsurus major and C. argentinus and the female adult of C. major are described for the first time and illustrated here; the male adults of both species are redescribed. A new species, C. amapaensis, is described from male imagos. The following new synonymies are proposed: Campsurus argentinus Esben-Petersen (= C. pallidus Needham & Murphy, junior synonym) and C. major Needham & Murphy (= C. brasiliensis Traver, junior synonym). The nymphs of both species are reported to use silk to build soft cases and to glue substrate particles. A list of characters useful to distinguish the treated species from others in the genus is given.     

Globus pallidus plays a critical role in neurotrophic factor induced functional improvements in hemiparkinsonian monkeys

This study was designed to test the hypothesis that the integrity of the globus pallidus (GP) is critical for neurotrophic factor, such as glial-derived neurotrophic factor (GDNF), induced functional changes in rhesus macaques with MPTP-induced parkinsonism, because our previous studies demonstrated that the GP was one of the most affected areas as assessed by the levels of dopamine (DA) and its metabolites. A group of eight hemiparkinsonian monkeys with pallidal lesions, which positively responsed to intraventricular (ICV) injections of GDNF prior to the lesions, and a group of eight hemiparkinsonian monkeys without pallidal lesions, were treated with GDNF after a long washout period after the initial ICV infusions of GDNF. Significant behavioral improvements were only seen in the monkeys without pallidal lesions that received GDNF. Monkeys with pallidal lesions failed to exhibit any behavioral improvement even though they had elevated nigral DA levels. The results suggest that the GP is critical for neurotrophic factor induced functional changes in PD monkeys.     

Parasitoid exploitation of the seasonal variation in host plant volatile emission for herbivore location

Volatile compounds from the apple, Malus domestica Borkh. (Rosaceae), change considerably as the season progresses, and this is successfully exploited by the female codling moth Cydia pomonella L. (Lepidoptera, Tortricidae), as it searches for oviposition sites. In this study, we investigated the effect of seasonal emissions of apple fruit volatiles on the host location behaviour of a parasitoid of the codling moth larvae, Hyssopus pallidus (Askew) (Hymenoptera: Eulophidae). In dual choice olfactory bioassays, the behaviour of the parasitoid in response to apple cues was observed over the complete 2003 growing season. Our results show that codling moth infested apples evoked a strong response from the parasitoid at the beginning of the season, until July. Then, attraction dropped drastically, increasing again at the beginning of August. At the end of the growing season, just prior to harvest, infested apples hardly evoked any behavioural response. Interestingly enough, mid‐season emissions of healthy apples were per se attractive to the parasitoid, and even preferred over volatiles from infested apples. Simultaneous volatile collections from healthy apples on twigs in the field were analysed throughout the season, showing that the overall quantity of headspace volatiles peaks at the beginning of June and mid‐August. The seasonal volatile emission is correlated with the behaviour of the parasitoid during the fruit ripening stage. The results are discussed in relation to the use of H. pallidus as a potential biocontrol agent, in order to enhance current integrated pest management (IPM) programs.     

深部脑刺激作用机制的探讨

深部脑刺激器（deep brain stimulator）,也经常被称为脑起搏器,是可植入人体设备,并连续不断地传送刺激脉冲到深部脑组织的特定区域,即所谓的深部脑刺激（deep brain stimulation,DBS）.迄今为止,深部脑刺激是治疗严重顽固抗药性运动障碍疾病（如帕金森病,原发性震颤及肌张力异常等）的最有效的外科治疗手段之一.此外,广大的科研工作者也不断地探索应用DBS治疗其他神经及精神异常（如,癫痫和强迫症）的新的临床应用.尽管应用DBS治疗运动障碍非常有效,并也迅速被探索性地应用到其他神经障碍治疗中,但其作用机制仍然不是十分清楚,成为学者们争论的热点.DBS治疗效果的作用机制通常有两种基本的观点：高频刺激抑制学说及高频刺激兴奋学说.基于最近发表的关于中枢神经系统内的高频刺激效应的资料、数据及相关评论,两种机制共存并发挥作用的DBS作用假说被提出,认为DBS通过施加高频刺激干扰并控制了核团病理性紊乱随机活动,同时施加兴奋性刺激到其他基底节的网络,以实现对帕金森病的治疗.