L\u2019ibridazione interspecifica: evidenze e limiti di un fenomeno ancora da comprendere

L\u2019interesse per l\u2019aspetto evoluzionistico dell\u2019ibridazione interspecifica \ue8 cresciuto negli ultimi anni, a giudicare dalla mole di articoli e review pubblicati sull\u2019argomento. Fili conduttori di questi lavori sono la considerazione dell\u2019ibridazione avvenuta e la conseguente ricerca delle evidenze che la dimostrano, siano esse morfologiche o genetiche: quasi mai l\u2019evento di ibridazione viene messo in discussione, neppure quando le specie coinvolte sono caratterizzate da sbilanciamenti aneuploidi molto forti. Generalmente, l\u2019ibridazione tra specie riconosciute come distinte \ue8 impedita dall\u2019innescarsi di meccanismi d\u2019isolamento pre e postzigotici. Questa incompatibilit\ue0 ci porta a mettere in discussione la facilit\ue0 con cui lo status di ibrido sia stato stabilito in questi lavori. Scopo della presente review \ue8 quello di investigare il trend del fenomeno nel tempo e i metodi utilizzati per analizzarlo. Prendendo come punto di partenza proprio l\u2019approccio teorico di Dobzhansky, abbiamo analizzato criticamente la letteratura disponibile al riguardo, privilegiando le indagini effettuate sui mammiferi e, in modo particolare, sui primati, data la constatazione che anche minime evidenze di aneuploidia sono non vitali nell\u2019uomo. Il database che ne abbiamo ricavato ci ha permesso di verificare come l\u2019interesse nei confronti dell\u2019ibridazione sia cresciuto nel tempo e quanto il numero di specie soggette ad ibridazione sia aumentato. Tuttavia, nonostante l\u2019evoluzione delle tecniche, alcuni lavori hanno privilegiato l\u2019approccio morfologico: discriminante, ma non sufficientemente risolutivo. Gli studi che, invece, hanno investigato l\u2019aspetto genetico si sono limitati a ricercare i riarrangiamenti cromosomici che caratterizzano l\u2019ibrido (supposto). La definizione di buona specie \ue8 spesso aleatoria, in quanto frutto di concetti che rappresentano categorie mentali. Non nascondendo che l\u2019introgressione possa essere considerata un valido meccanismo di speciazione, non crediamo, tuttavia, che esso possa manifestarsi cos\uec facilmente in specie caratterizzate da profonde differenze genomiche. Riteniamo che ulteriori indagini \u2013 in particolare, mediante approcci come l\u2019ibridazione in situ miranti al confronto di ampie aree cromosomiche di omologia - siano necessarie per approfondire le nostre conoscenze su un fenomeno ancora in gran parte da comprendere

La phylog\ue9nie des cercopithecin\ue9s encore en costruction.

Les cercopithecines (guenons et autres taxa corr\ue9l\ue9es) sont un groupe de singes africains qui se composent d'environ 36 r\ue9elles esp\ue8ces avec une \ue9volution et une phylog\ue9nie tr\ueas difficile \ue0 reconstruire. L\u2019approche scolaire a la tendance \ue0 proposer la clusterisation du groupe en question en deux: strictement arboricoles et terrestres. Avec la pr\ue9sente, nous analysons de fa\ue7on critique les diff\ue9rentes reconstructions phylog\ue9n\ue9tiques propos\ue9es aujourd\u2019hui tout en conduisant une analyse sur la base des aspects mol\ue9culaires, chromosomiques et \ue9cologiques des esp\ue8ces incluses dans le "groupe d'esp\ue8ces" actuellement reconnu. Cette approche multidisciplinaire inclue la morphologie, l'\ue9cologie r\ue9gionale ainsi que les r\ue9sultats des recherche s conduites dans les zones g\ue9ographiques d\u2019appartenance et d\ue9montre l'incoh\ue9rence e l\u2019insuffisance du point de vue traditionnel

Recurrent deficit irrigation and fruit harvest affect tree water relations and fruitlet growth in ‘Valencia’ orange

Background. Partial rootzone drying is an irrigation strategy known for increasing water use efficiency without significantly affecting tree water status. ‘Valencia’ oranges have a very long development period and nearly mature fruit and new fruitlets may be present at the same time on the tree, competing for water and assimilates. Objectives. The present study investigates the effect of recurrent deficit irrigation and fruit harvest on tree water status and fruitlet growth of ‘Valencia’ orange. Methods. Forty-eight adult trees were exposed to three irrigation treatments for seven years (2007-2013): irrigation with 100% of ETc (CI), continuous deficit irrigation (DI, 50% of CI) and partial root-zone drying (PRD, 50% of CI on alternated sides of the root-zone). In spring 2014, stem water potential (Ψstem) and continuous measurements of sap flow and fruitlet growth were recorded before (May) and after (June) the harvest of mature fruit. Results. No differences in Ψstem were found among irrigation treatments, while Ψstem was lower in June than in May at midday. In both May and June, sap flow density (not sap flow per tree) was higher in DI than in CI and PRD trees suggesting more efficient water uptake/transport in the former. In May, DI and PRD fruit showed lower daily relative growth rate (RGR) than CI fruit due to a possible shortage of carbon and nutrients. After removing mature fruits, differences among irrigation treatments were canceled. Sap flow was directly related to fruit RGR at low sap flow rates, but inversely related to RGR at high sap flow rates. Conclusions. Our data show that the presence of maturing fruit does not impact the water status of ‘Valencia’ trees, while it may transiently limit fruitlet growth (by source limitation) in deficit irrigated trees

Tensor variational inequalities: Theoretical results, numerical methods and applications to an economic equilibrium model

The paper deals with the study of tensor variational inequalities. and some projection methods to solve them. In particular, some properties on the solutions to such an inequality are established and a fixed point theorem is proved. Moreover, some numerical methods are introduced and the convergence analysis of them is investigated. All the theoretical results are applied to analyze a general oligopolistic market equilibrium problem in which each firm produces several commodities and has some production excesses since the equilibrium condition is characterized by means of a tensor variational inequality. A numerical example is also discussed

Internationalization: Towards New Horizons

AbstractThis article aims to examine the internationalization actions of Brazilian Postgraduate Programs. Data were used from the Coordination for the Improvement of Higher Education Personnel (CAPES) and the Ministry of Education (MEC), which perform an evaluation of postgraduate courses every three years. Recently, the period was changed to four years. The data reported in the Indicators Booklet of productions of each program, selected according to 8 criteria, allowed the grouping of activities. The comments made on the Evaluation Form were then examined. This showed that internationalization actions are varied and are overwhelmingly present in the Brazilian programs (n= 49). It was verified that the evaluation valorizes production in international publications, often to the detriment of the various actions that effectively contribute to internationalization. It was concluded that, despite publication in international media being a relevant indicator, it does not definitively indicate participation in international knowledge production. The demand, on behalf of students and researchers, for the qualification that is provided in the country would be the most accurate indicator of internationalization. No courses, in the period examined, accommodated non-Portuguese speakers. Despite the efforts already made toward effective internationalization, there remains the important and urgent step: to make the National Postgraduate System a reference point in the international community

A two-phase problem with Robin conditions on the free boundary

We study for the first time a two-phase free boundary problem in which the solution satisfies a Robin boundary condition. We consider the case in which the solution is continuous across the free boundary and we prove an existence and a regularity result for minimizers of the associated variational problem. Finally, in the appendix, we give an example of a class of Steiner symmetric minimizers

Serum Anti-Thyroglobulin Autoantibodies Are Specific in Predicting the Presence of Papillary-like Nuclear Features and Lymphocytic Infiltrate in the Thyroid Gland

(1) Background: Previous studies have reported a correlation between serum anti-Thyroglobulin-antibodies (TgAb) and papillary thyroid carcinoma. The aim of our study was to evaluate whether serum TgAb and anti-thyroid-peroxidase antibody (TPO) positivity was also related to pre-neoplastic histological changes such as papillary-like nuclear features (PLNF) and with the presence of lymphocytic infiltrate (LI) in thyroid surgical specimens. (2) Methods: The study was retrospectively carried out on 70 consecutively recruited patients who underwent thyroidectomy for benign process and whose TgAb and TPOAb values were retrieved from clinical records. Histological sections of thyroid surgical samples were revised, looking for PLNF and lymphocytic infiltrate. HBME1 expression was assessed by immunohistochemistry. (3) Results: Our results showed a significant association between TgAb, PLNF, and lymphocytic infiltrate. The presence of TgAb was highly specific, but less sensitive, in predicting the presence of PLNF (sensitivity = 0.6, specificity = 0.9; positive predictive value (PPV) = 0.88; negative predictive value (NPV) = 0.63). TgAb positivity showed a good association with the presence of lymphocytic infiltrate (sensitivity = 0.62, specificity = 0.9; PPV = 0.88 and NPV = 0.68). HBME1 immunoreactivity was observed in the colloid of follicles showing PLNF and/or closely associated with LI. (4) Conclusions: The presence of PLNF and LI is associated with serum TgAb positivity. The presence of TgAb and of LI could be triggered by an altered thyroglobulin contained in the HBME1-positive colloid, and could be a first defense mechanism against PLNF that probably represent early dysplastic changes in thyrocytes

A cross-country examination on the fear of covid-19 and the sense of loneliness during the first wave of covid-19 outbreak

The aim of the current study is to examine gender, age. and cross-country differences in fear of COVID-19 and sense of loneliness during the lockdown, by comparing people from those countries with a high rate of infections and deaths (e.g., Spain and Italy) and from countries with a mild spread of infection (e.g., Croatia, Serbia, Slovakia, Slovenia, and Bosnia and Herzegovina). A total of 3876 participants (63% female) completed an online survey on “Everyday life practices in COVID-19 time” in April 2020, including measures of fear of COVID-19 and loneliness. Males and females of all age groups in countries suffering from the powerful impact of the COVID-19 pandemic reported greater fear of COVID-19 and sense of loneliness. In less endangered countries, females and the elderly reported more symptoms than males and the young; in Spanish and Italian samples, the pattern of differences is considerably more complex. Future research should thoroughly examine different age and gender groups. The analysis of emotional well-being in groups at risk of mental health issues may help to lessen the long term social and economic costs due to the COVID-19 outbreak