Rate of synthesis of nucleic acids and their precursors in developing ovaries of Galleria mellonella

Three groups of ovarioles were selected for study: previtellogenetic (I), those in the course of vitellogenesis (II), and postvitellogenetic (III). Previtellogenetic ovarioles showed the highest content of DNA and acid-soluble nucleotide fraction. The mean rate of incorporation of [³H]-thymine into the mononucleotide fraction within 2·5 min mainly depends on the rate of transport of the pyrimidine base into the ovarioles, and was found to be highest (35 × 10⁴ dis/min per μmole of nucleotide per min) in vitellogenetic ovarioles. The rate for [³H]-uracil is highest in previtellogenetic ovarioles.Incorporation of pyrimidine bases into the polynucleotide fraction was corrected for the mononucleotide pool available for synthesis. [³H]-Thymine is incorporated into the polynucleotide fraction most actively in group III of the ovarioles, being probably restricted to numerous follicular cells, whereas [³H]-uracil is mainly incorporated during vitellogenesis.     

Holocene forest dynamics and human impact in southeastern Estonia

Litho-, chrono- and biostratigraphical methods were applied in the examination of a 9.9 m thick sequence of laminated sediments in Verijärv, a lake in southeast Estonia. The vegetation history, which covers at least the time from 10300 cal b.p. to the present, was inferred from the core, which was taken from the deepest part of the lake and correlated with the studied and dated pollen diagrams nearby. Reconstruction of the past vegetation dynamics is based on pollen percentage, accumulation rate and human impact diagrams. During the Holocene two main shifts in vegetation dynamics occurred, the first one at about 7700 cal b.p. when the pine-birch forest was replaced by deciduous mixed forest, and the second at about 3200 cal b.p. marked by the regeneration of pine-birch-spruce forest. A catastrophic forest fire at about 3450 cal b.p. opened up the landscape and gave rise to erosion and the sedimentation of a thick clayey layer. The steep decline in the Alnus curve between 1500–1650 cal b.p. coincides with the start of the continuous Secale curve and evidence of extensive land-use.     

质粒拯救法克隆细菌基因组大片段

[目的]细菌基因组大片段尤其是基因簇的克隆与操作,是细菌基因功能分析的一个难点.基因组测序工作的不断完成和序列信息的大量积累,为细菌基因组:DNA的操作提供了方便.本文报道了利用细菌的全基因组信息和质粒拯救法的原理建立的一种克隆细菌基因组大片段的方法.[方法]首先,根据基因组序列信息,在待克隆片段的一侧扩增一段DNA,并将其克隆到自杀载体上构建打靶质粒,然后,将打靶质粒整合到细菌的基因组中构建重组菌,提取重组菌的基因组DNA,酶切,自连,转化,将自杀质粒与待克隆的目的片段一起拯救出来.最后,根据需要将拯救的DNA片段亚克隆到新的载体中.[结果]我们利用该方法克隆了布鲁氏菌中长度为11kb的virB操纵子,并构建了互补质粒.将该质粒导入到virB的突变株中后使virB操纵子的转录活性得到了恢复,表明该策略切实可行.[结论]这种重组克隆策略给我们提供了一种新的对细菌基因组大片段进行操作的方法.     

Investigating key cell types and molecules dynamics in PyMT mice model of breast cancer through a mathematical model

The most common kind of cancer among women is breast cancer. Understanding the tumor microenvironment and the interactions between individual cells and cytokines assists us in arriving at more effective treatments. Here, we develop a data-driven mathematical model to investigate the dynamics of key cell types and cytokines involved in breast cancer development. We use time-course gene expression profiles of a mouse model to estimate the relative abundance of cells and cytokines. We then employ a least-squares optimization method to evaluate the model’s parameters based on the mice data. The resulting dynamics of the cells and cytokines obtained from the optimal set of parameters exhibit a decent agreement between the data and predictions. We perform a sensitivity analysis to identify the crucial parameters of the model and then perform a local bifurcation on them. The results reveal a strong connection between adipocytes, IL6, and the cancer population, suggesting them as potential targets for therapies.     

New evidence of possible crop introduction to north-eastern Europe during the Stone Age

Long term (from the Mesolithic to the Bronze Age) habitation of the Akali settlement on a clearly defined bog-island in East Estonia is used as an example of transitional development from a prosperous foragers’ habitation centre to a hinterland of established farming cultures, taking place through availability, substitution and consolidation phases of crop farming in the boreal forest zone. The pre-Neolithic finds of Triticum and Cannabis t. pollen at c. 5600 b.c. are interpreted as possible indications of the acquaintance of foragers with farming products, through contacts with central European agrarian tribes during the availability phase. The substitution phase is marked by more or less scattered pollen finds of various cereals and hemp and, at Akali, is connected with Neolithic period 4900–1800 b.c. An increasing importance of crop farming in the economy is characteristic of the consolidation phase, but because natural conditions are unfavourable for arable land-use, a regression of human presence is recorded during the second part of the Neolithic. The settlement was abandoned during the Bronze Age at the time when crop farming become the basis of the economy in Estonia. The re-colonisation of the area, traced to ca. a.d. 1200, took place for political reasons rather than through increasing suitability of the landscape.Editorial responsibility: Felix Bittmann     

Multiple-source models for electron beams of a medical linear accelerator using BEAMDP computer code

AimThe aim of this work was to develop multiple-source models for electron beams of the NEPTUN 10PC medical linear accelerator using the BEAMDP computer code.BackgroundOne of the most accurate techniques of radiotherapy dose calculation is the Monte Carlo (MC) simulation of radiation transport, which requires detailed information of the beam in the form of a phase-space file. The computing time required to simulate the beam data and obtain phase-space files from a clinical accelerator is significant. Calculation of dose distributions using multiple-source models is an alternative method to phase-space data as direct input to the dose calculation system.Materials and methodsMonte Carlo simulation of accelerator head was done in which a record was kept of the particle phase-space regarding the details of the particle history. Multiple-source models were built from the phase-space files of Monte Carlo simulations. These simplified beam models were used to generate Monte Carlo dose calculations and to compare those calculations with phase-space data for electron beams.ResultsComparison of the measured and calculated dose distributions using the phase-space files and multiple-source models for three electron beam energies showed that the measured and calculated values match well each other throughout the curves.ConclusionIt was found that dose distributions calculated using both the multiple-source models and the phase-space data agree within 1.3%, demonstrating that the models can be used for dosimetry research purposes and dose calculations in radiotherapy.     

Comparing the Recurrence of Vulvovaginal Candidiasis in Patients Undergoing Prophylactic Treatment with Probiotic and Placebo During the 6 Months

This is a randomized, double-blind, clinical/comparative trial study, involving the recurrence of vaginal candidiasis (VVC) after initial treatment with oral fluconazole in patients undergoing prophylactic management with a probiotic and placebo for 6 months. Fifty-nine VVC patients who were diagnosed based on their history, physical examination, and culture of vaginal discharge were initially treated by a single dose of 150 mg fluconazole. According to the table of random numbers, the sample was divided into two groups. The patients from one group took probiotics, while those from the other group took a placebo, with all of them being continuously monitored for 6 months. The patients complaining of vaginal candidiasis symptoms, such as burning, pruritus, and a vaginal (curd-like) discharge, were examined and the discharge was cultured for candida. The positive cultures were considered to be recurring for the patients in each group. Thirty-one cases from the placebo group and 28 cases from the probiotic group were carefully observed. In total, the 6-month recurrence in the control group was eleven (35.5 %) and in the research group was two (7.2 %). The results from Fisher’s exact test for the value p = 0.01 and OR 0.14 95 % CI (0.028–0.7) showed significant recurrence in the placebo group. The findings demonstrated that taking probiotics withazole antifungal drugs could be highly effective in treating VVC, resulting in a lower recurrence rate as well.     

Expression of α2, α5 and α6 subunits of integrin in de-differentiated NIH3T3 cells by cell-free extract of embryonic stem cells

Generation of patient specific stem cells is among the ultimate goals in regenerative medicine. Such a cell needs to be functional when it transplants. Interaction between the matrix proteins and integrin adjust many cells' function such as adhesion, migration, cell cycle and self renewal in stem cells. In this study, NIH3T3 cells were dedifferentiated by mouse Embryonic Stem Cell (mESC) extract. The expression of pluripotency markers as well as a2, a5 and a6 integrin subunits were determined. NIH3T3 cells treated with mESC extract showed noticeable changes in cell morphology as early as day 2 post-treatment forming colonies similar to typical mESC morphology by day 8, after three passages. Alkaline phosphatase (ALP) assay and immunocytochemistry staining were performed for the induced reprogrammed cells. The results indicated that these colonies showed the ALP activity and they express Sox2 and Nanog. RT-PCR revealed that the colonies also express Oct3/4. NIH3T3 cells, ESC and reprogrammed cells expressed a2 integrin. a5 integrin expression was greatest in reprogrammed cells followed by the expression of this integrin in NIH3T3 which in turn was more than in ESC. a6A integrin was expressed in NIH3T3 cells while a6B integrin was expressed in ESC and in very low quantity was expressed in reprogrammed cells. These data provide evidence for both the generation of ES like cells from differentiated somatic cells and the expression profile of integrins after de-differentiation by mESC extract.     

Modeling Cell Dynamics in Colon and Intestinal Crypts: The Significance of Central Stem Cells in Tumorigenesis

Colon and intestinal crypts have been widely chosen to study cell dynamics because of their fairly simple structures. In the colon and intestinal crypts, stem cells (SCs) are located at very bottom of the crypt, fully differentiated cells (FDs) are located in the top of the crypt, and transit-amplifying cells (TAs) are in the middle of the crypt between FDs and SCs. Recently, it has been discovered that there are two types of stem cells in the intestinal crypts: central stem cells (CeSCs) and border stem cells. To investigate dynamics of mutants in colon and intestinal crypts, we develop a four-compartmental stochastic model, which includes two SC compartments, and TAs and FDs compartments. We calculate the probability of the progeny of marked or mutant cells located at each of these compartments taking over the entire crypt or being washed out from the crypt. We found that the progeny of CeSCs will take over the entire crypt with a probability close to one. Interestingly, the progeny of advantageous mutant TAs and FDs will be washed out faster than disadvantageous mutants. Saliently, the model predicts that the time that the progeny of wild-type central stem cells will take over the mouse intestinal crypt is around 60 days, which is in perfect agreement with an experimental observation.