AUTORADIOGRAPHIC STUDY OF DNA SYNTHESIS AND THE CELL CYCLE IN SPERMATOGONIA AND SPERMATOCYTES OF MOUSE TESTIS USING TRITIATED THYMIDINE

Mice were injected intraperitoneally with 15 µc of H3-thymidine. The time course of the labeling in spermatogonia and spermatocytes was studied by using autoradiography on 5 µ sections stained by the periodic acid-Schiff method and hematoxylin over a period of 57 hours after injection. Four generations of type A (called AI, AII, AIII, and AIV), one of intermediate, and one of type B spermatogonia occur in one cycle of the seminiferous epithelium. The average life span is about the same in all spermatogonia, i.e., about 27 to 30.5 hours. The average pre-DNA synthetic time, including the mitotic stages from metaphase through telophase and the portion of interphase preceding DNA synthesis, is also not very different, ranging between 7.5 and 10.5 hours. A remarkable difference exists, however, in the duration of DNA synthesis and of the post-DNA synthetic period. The average DNA synthetic time is very long and is highly variable in type B (14.5 hours), a little shorter and less variable in intermediate (12.5 hours) and AIV (13 hours) spermatogonia, and much shorter and very constant in AIII (8 hours), AII and AI (7 to 7.5 hours) spermatogonia. Conversely, the average post-DNA synthetic time, corresponding essentially to the duration of the prophase, is short and very constant in type B (4.5 hours), longer and variable in intermediate (6 hours) and AIV (8 hours) spermatogonia, and much longer and much more variable in AIII (11 hours), AII and AI (14 hours) spermatogonia. The premeiotic synthesis of DNA takes place in primary spermatocytes during the resting phase and terminates just before the visible onset of the meiotic prophase. Its average duration is 14 hours. No further synthesis of DNA takes place in later stages of spermatogenesis

Bradysia hygida (Diptera, Sciaridae) presents two eukaryotic Elongation Factor 1A gene homologues: partial characterization of the eukaryotic Elongation Factor 1A-F1 gene

Elongation factor 1A is a highly conserved protein that participates in translation. We report the occurrence of two genes homologous to the eukaryotic Elongation Factor 1A in Bradysia hygida and describe the partial cloning and characterization of the B. hygida eukaryotic Elongation Factor 1A-F1 (BheEF1A-F1) gene. The pattern of BheEF1A-F1 expression in the salivary gland at the end of the fourth larval instar was investigated using real-time PCR. The results showed that BheEF1A-F1 expression levels are relatively constant at the time when rapid changes in protein synthesis occur in this tissue. In situ hybridization experiments coupled to Southern blot analyses showed that the BheEF1A-F1 gene is located at position 3d of the A chromosome and a second gene homologous to eEF1A is located at position 6a of the X chromosome. Southern blot analyses showed that both the BheEF1A-F1 gene and the second gene homologous to eEF1A constitute non-amplified genes. The present results contribute to the molecular characterization of a sciarid eEF1A gene

MAGNETOSTRATIGRAPHIC DATA ON THE FIRST COLONIZATION OF EUROPE BY EARLY HOMININS DURING THE LATE EARLY PLEISTOCENE.

It is generally accepted in the paleoanthropological literature that the colonization of Europe by early hominins, intended as Homo erectus derived forms such as Homo heidelbergensis, occurred before the last magnetic polarity reversal that is dated back to 0.78 Ma and marks the transition form the Matuyama reversal polarity chron to the actual normal polarity chron known as Brunhes. The still ongoing debate concerns the possibility for early hominins to have firmly settled in Europe before 1 Million years ago. All the European sites presenting proper chronologies put the first convincing evidence of human occupation during the latter part of the Matuyama reverse polarity chron spanning from the top of Jaramillo normal polarity subchron (0.99 Ma) to the base of the Brunhes normal polarity chron (0.78 Ma). It seems therefore plausible that the first stable human residents came to Europe during the latter part of the Matuyama reverse polarity chron. This relatively brief period of time coincided with a major reorganization of the changing environmental conditions in Europe and elsewhere known as the Early late Pleistocene climate Revolution (EPR). The EPR coincided with the onset of the major Pleistocene glaciation in the Northern hemisphere that triggered the modification of the drainage patterns and consequently brought the formation of the modern fluvial systems especially the Danube in Eastern Europe and the Po in Italy. These environmental changes brought to the formation of new habitats characterized by lowlands colonized by grasslands during glacial/interglacial transitions, while steppic loess environments characterized full glacial periods and closed temperate forests full interglacial periods. The EPR caused also a faunal turnover as a consequence to the environmental changes, species adapted to a closed forest environment belonging to the so-called Villafranchian faunal association were substituted with species more adapted to the newly formed environments belonging to the so-called Galerian faunal association. It seems probable that the opening of the Danube-Po getaway constituted a fundamental element for the migrations of these animals and of early hominins to take place from Africa/Levant across the Balkans into southern Europe since MIS 22. After providing an initial review of the chronology presented for the sites manifesting human occupation of the Mediterranean area we investigated five new sites in order to provide new evidences that will substantiate the hypothesis of the colonization of Europe by early hominins not antecedent the EPR following the Danube-Po migration pathway. The first site is the Arda river section in northern Italy that provides a continuous record of the transition from marine sedimentation typical of the Pliocene-Early Pleistocene to late Early Pleistocene-Holocene continental sedimentation. Even though no human evidences have yet be found in this locality the discovery mammal layer with a mixed Villafranchian-Galerian faunal assemblage just preceding the EPR proves the first contact that occurred between these two faunal associations. The second investigated site is Kostolac, in Serbia, that even thus not revealing any evidence of human occupation, strongly supports the \u201cfollow the herd\u201d hypothesis since it yields the first occurrence of the Mammuthus trogontherii in the Pannonian region just before the Brunhes-Matuyama boundary at the bottom of a loessic sequence. This suggests that the first income of this species in the investigated region occurred just after the EPR taking advantage of the Danube-Po gateway. The third presented site is the stratigraphic sequence from the cave of Kozarnika in Northern Bulgaria. Evidences of human occupation of the cave are known throughout the entire stratigraphic sequence as far down as the bottom of the loess deposit that is located between the Jaramillo normal magnetic polarity subchron and the Brunhes normal polarity. The acquired data strongly support the idea that the income of hominins in the investigated region started with MIS 22 along the Danube drainage system from the Black sea into Europe. The fourth investigated site it the Greek site of Megalopolis where an archeological site bearing a specimen of Elephas antiquus with slaughtering evidences lies in an alternation between lignite and sediment levels. The Brunhes-Matuyama boundary lies at the bottom of the sequence but there is no evidence yet of human occupation of the area during the critic time lapse for this study. Strong evidence of the connection between the variation in the deposited facies and the glacial-interglacial cycles was observed therefore we dated the archeological site back to 3c450 ky. The last investigated site is the deposit of the Prince\u2019s cave near Ventimiglia (Northern Italy), where a preneanderthalian human ilium was found in a complex stratigraphic context. Only normal magnetic polarity, interpreted as the Brunhes chron, was observed throughout the entire sequence that was therefore attributed to the middle Pleistocene. Evidences on the oldest units deposited in the cave jointly with the uplift rates for that region suggest that the cave was probably submerged during the EPR and therefore no human frequentation was possible in this site before MIS 7. Except for the Prince\u2019s cave deposit, whose age resulted being to young, all the other sites give evidences of the colonization of Europe by early hominins not antecedent MIS 22 following the Danube-Po migration pathway, therefore supporting the central role of the EPR in the first stable peopling of the European continent

Structural dichroism in the antiferromagnetic insulating phase of V_2O_3

We performed near-edge x-ray absorption spectroscopy (XANES) at V K edge in the antiferromagnetic insulating (AFI) phase of a 2.8% Cr-doped V_2O_3 single crystal. Linear dichroism of several percent is measured in the hexagonal plane and found to be in good agreement with ab-initio calculations based on multiple scattering theory. This experiment definitively proves the structural origin of the signal and therefore solves a controversy raised by previous interpretations of the same dichroism as non-reciprocal. It also calls for a further investigation of the role of the magnetoelectric annealing procedure in cooling to the AFI phase.Comment: 4 pages 3 figures. To be published in Phys. Rev. B (2005

Factors influencing consumer decision-making in choosing a channel to remit in South Africa

This research was conducted to provide insights into the factors that influence consumer’s decision when choosing a channel to remit. The study looked at the following theories in determining the important factors that influence consumer intention or behavior, Theory of Reason Action, Theory of Planned Action, Remittance, Innovation Diffusion and Technology Acceptance Models. Hence, service providers should be aware of these factors so they can develop strategies and services to attract consumers to use their channels. The aim of the study was to determine which factors influence consumer’s decision in choosing a bank and non-bank channel to remit. The investigation of the key factors that influence the decision or intention, it was found that a single factor influenced the decision to remit in a bank and non-bank channel. It was also found in the study that consumers prefer physical channel of both bank and non-bank to remit. The finding has serious implications for service providers, in that consumer behavior show attachment to traditional distribution channels.Dissertation (MBA)--University of Pretoria, 2011.Gordon Institute of Business Science (GIBS)unrestricte

Ecce Homo in Milan

Come ogni essere vivente anche l\u2019uomo ha colonizzato gli habitat solo nel momento in cui questi presentavano le condizioni favorevoli alla sua sopravvivenza. La colonizzazione del continente europeo \ue8 avvenuta molto probabilmente da Est verso Ovest e l\u2019ingresso in Italia pu\uf2 essere avvenuto solo dal punto pi\uf9 comodo in cui si poteva superare la catena Alpina, ossia passando dai Balcani (Figura 2). Dal record geologico si deduce il susseguirsi di periodi caldi a periodi freddi durante tutto il Pleistocene, tuttavia non ci sono evidenze di un passaggio ad un clima glaciale nel nostro paese prima del Pleistocene Superiore. Questo cambiamento ha come prima conseguenza l\u2019espansione delle calotte glaciali legata all\u2019intrappolamento dell\u2019acqua degli oceani e il conseguente abbassamento del livello del mare che provoca il passaggio di molte zone precedentemente sommerse prima ad un ambiente litorale e inne emerso. Questo \ue8 quanto si \ue8 vericato in Pianura Padana. Il cambiamento di ambiente ha provocato una variazione nel materiale che si stava depositando: prima si avevano limi e sabbie marine, poi ciottoli legati al trasporto uviale e materiale ne legato alle esondazioni dei umi. La dierenza nel materiale deposto \ue8 stata riconosciuta lungo tutta la Pianura Padana ed \ue8 stata nominata Discontinuit\ue0 R. La Discontinuit\ue0 R \ue8 quindi legata a un cambiamento nel clima, e all\u2019istaurarsi delle grandi glaciazioni nel continente europeo. Mediante lo studio di diverse carote prelevate in Pianura Padana \ue8 stato possibile creare un modello di et\ue0 che ha permesso di associare la Discontinuit\ue0 R al MIS22, datandola a circa 870.000 anni fa (Figura 1). Il MIS22 corrisponde inoltre alla ne della cosiddetta \u201cRivoluzione del Pleistocene Medio\u201d, un momento in cui si \ue8 assistito ad un cambiamento nella ora con la comparsa delle prime piante legate all\u2019ambiente glaciale, ma anche ad un cambiamento nella fauna legato all\u2019arrivo di specie come il mammuth (Mammuthus meridionalis), l\u2019elefante antico (Elephas antiquus), e il rinoceronte lanoso (Coelodonta antiquitatis). La nostra ipotesi \ue8 che l\u2019arrivo dell\u2019uomo in Europa e in Italia sia stato legato alla sua tendenza a seguire le onde migratorie degli animali che costituivano le sue principali prede (Figura 2), e che sia avvenuto in concomitanza con l\u2019instaurarsi delle grandi glaciazioni Pleistocenica, ossia attorno all\u2019et\ue0 del MIS22

Functional characterization of the sciarid BhC4-1 core promoter in transgenic Drosophila

<p>Abstract</p> <p>Background</p> <p>Core promoters are <it>cis</it>-regulatory modules to which bind the basal transcriptional machinery and which participate in the regulation of transcription initiation. Although core promoters have not been extensively investigated through functional assays in a chromosomal context, the available data suggested that the response of a given core promoter might vary depending on the promoter context. Previous studies suggest that a (-57/+40) fragment constitutes the core promoter of the <it>BhC4-1 </it>gene which is located in DNA puff C4 of the sciarid fly <it>Bradysia hygida</it>. Here we tested this (-57/+40) fragment in distinct regulatory contexts in order to verify if promoter context affects its core promoter activity.</p> <p>Results</p> <p>Consistent with the activity of a core promoter, we showed that in the absence of upstream regulatory sequences the (-57/+40) fragment drives low levels of reporter gene mRNA expression throughout development in transgenic <it>Drosophila</it>. By assaying the (-57/+40) fragment in two distinct regulatory contexts, either downstream of the previously characterized <it>Fbp1 </it>enhancer or downstream of the UAS element, we showed that the <it>BhC4-1 </it>core promoter drives regulated transcription in both the germline and in various tissues throughout development. Furthermore, the use of the <it>BhC4-1 </it>core promoter in a UAS construct significantly reduced salivary gland ectopic expression in third instar larvae, which was previously described to occur in the context of the GAL4/UAS system.</p> <p>Conclusions</p> <p>Our results from functional analysis in transgenic <it>Drosophila </it>show that the <it>BhC4-1 </it>core promoter drives gene expression regardless of the promoter context that was assayed. New insights into the functioning of the GAL4/UAS system in <it>Drosophila </it>were obtained, indicating that the presence of the SV40 sequence in the 3' UTR of a UAS construct does not preclude expression in the germline. Furthermore, our analysis indicated that ectopic salivary gland expression in the GAL4/UAS system does not depend only on sequences present in the GAL4 construct, but can also be affected by the core promoter sequences in the UAS construct. In this context, we propose that the sciarid <it>BhC4-1 </it>core promoter constitutes a valuable core promoter which can be employed in functional assays in insects.</p

Magnetostratigraphy Of The Pleistocene Arda River Section (Northern Italy)

We investigated the magnetic properties of the Pleistocene sediments exposed in the Arda river section in southern Po plain, northern Italy. This site contains a complete record of the transition occurring in the greater Po basin between marine sedimentation typical of the Early Pleistocene and continental sedimentation typical of the Middle-Late Pleistocene. The study of the magnetic mineralogy shows a dominance of Magnetite as the main magnetic mineral in almost the whole sequence except for the top where it changes into Hematite and for two minor intervals at the base and the middle of the sequence where the signal is carried mainly by sulphides. Five magnetic polarity reversals were recognized and used to construct an age model of sedimentation for the whole sequence, which was found to span in substantial stratigraphic continuity between ~2.5 Ma in the Matuyama chron across the Olduvai subchron, the Jaramillo subchron to the Brunhes-Matuyama boundary at 0.78 Ma, the correct interpretation of these magnetostratigraphic data has been proven by biostratigraphic data collected at the same time as the paleomagnetic sampling. According to this age model, the age of continentalization occurred in this area between the top of the Jaramillo (0.99 Ma) and the Brunhes-Matuyama boundary (0.78 Ma) and during the late Early Pleistocene climate revolution (EPR). Using magneto-lithostratigraphic data from other sections from the literature outcropping nearby, we reconstructed the timing of continentalization of the greater Po basin area during the EPR. The comparison between data coming form different sections in the Po basin prove a slight diachrony in the marine-continental transtition occurring from the western to the eastern part of the plain due to the gradual infilling by continental sediments. This age for the continentalization of the northern italian area combines well with the age of the best-dated sites with evidence of the earliest peopling of Europe