Deformation of stem cell nuclei by nanotopographical cues.

Cells sense cues in their surrounding microenvironment. These cues are converted into intracellular signals and transduced to the nucleus in order for the cell to respond and adapt its function. Within the nucleus, structural changes occur that ultimately lead to changes in the gene expression. In this study, we explore the structural changes of the nucleus of human mesenchymal stem cells as an effect of topographical cues. We use a controlled nanotopography to drive shape changes to the cell nucleus, and measure the changes with both fluorescence microscopy and a novel light scattering technique. The nucleus changes shape dramatically in response to the nanotopography, and in a manner dependent on the mechanical properties of the substrate. The kinetics of the nuclear deformation follows an unexpected trajectory. As opposed to a gradual shape change in response to the topography, once the cytoskeleton attains an aligned and elongation morphology on the time scale of several hours, the nucleus changes shape rapidly and intensely.

Diet-induced obesity alters the differentiation potential of stem cells isolated from bone marrow, adipose tissue and infrapatellar fat pad: the effects of free fatty acids.

INTRODUCTION: Obesity is a major risk factor for several musculoskeletal conditions that are characterized by an imbalance of tissue remodeling. Adult stem cells are closely associated with the remodeling and potential repair of several mesodermally derived tissues such as fat, bone and cartilage. We hypothesized that obesity would alter the frequency, proliferation, multipotency and immunophenotype of adult stem cells from a variety of tissues. MATERIALS AND METHODS: Bone marrow-derived mesenchymal stem cells (MSCs), subcutaneous adipose-derived stem cells (sqASCs) and infrapatellar fat pad-derived stem cells (IFP cells) were isolated from lean and high-fat diet-induced obese mice, and their cellular properties were examined. To test the hypothesis that changes in stem cell properties were due to the increased systemic levels of free fatty acids (FFAs), we further investigated the effects of FFAs on lean stem cells in vitro. RESULTS: Obese mice showed a trend toward increased prevalence of MSCs and sqASCs in the stromal tissues. While no significant differences in cell proliferation were observed in vitro, the differentiation potential of all types of stem cells was altered by obesity. MSCs from obese mice demonstrated decreased adipogenic, osteogenic and chondrogenic potential. Obese sqASCs and IFP cells showed increased adipogenic and osteogenic differentiation, but decreased chondrogenic ability. Obese MSCs also showed decreased CD105 and increased platelet-derived growth factor receptor α expression, consistent with decreased chondrogenic potential. FFA treatment of lean stem cells significantly altered their multipotency but did not completely recapitulate the properties of obese stem cells. CONCLUSIONS: These findings support the hypothesis that obesity alters the properties of adult stem cells in a manner that depends on the cell source. These effects may be regulated in part by increased levels of FFAs, but may involve other obesity-associated cytokines. These findings contribute to our understanding of mesenchymal tissue remodeling with obesity, as well as the development of autologous stem cell therapies for obese patients.

Radiation responses of stem cells: targeted and not-targeted effects

Stem cells are fundamental to the development of any tissue or organism via their ability to self-renew, which is aided by their unlimited proliferative capacity and their ability to produce fully differentiated offspring, often from multiple lineages. Stems cells are long lived and have the potential to accumulate mutations, including in response to radiation exposure. It is thought that stem cells have the potential to be induced into a cancer stem cell phenotype and that these may play an important role in resistance to radiotherapy. For radiation-induced carcinogenesis, the role of targeted and non-targeted effects is unclear with tissue or origin being important. Studies of genomic instability and bystander responses have shown consistent effects in haematopoietic models. Several models of radiation have predicted that stem cells play an important role in tumour initiation and that bystander responses could play a role in proliferation and self-renewal.

Occurrence of stem-pitting strains of Citrus tristeza virus in Croatia

Citrus is grown in Croatia (approximately 1,500 ha of citrus groves) on the Dalmatian Coast and Islands between 42 and 43°30'N. The major species, Citrus unshiu Marc. (Satsuma mandarin), is grafted on trifoliate rootstock. The presence of Citrus tristeza virus (CTV) in Satsumas in the Neretva Valley Region was previously reported (3). During the course of a biomolecular characterization of isolates from Croatia, 15 budsticks were collected from field- infected, enzyme-linked immunosorbent assay (ELISA)-positive sources during the autumn of 2003 near Kaštela, Split, Metković (Neretva Valley), and on the island of Vis. Isolates were propagated by graft transmission to Madam Vinous sweet orange (SwO) and maintained in an insect-proof greenhouse at 21 to 33° C.

Diameter of parallelogramic honeycomb torus

The determination of the diameter of an interconnection network is essential in evaluating the performance of the network. Parallelogramic honeycomb torus is an attractive alternative to classical torus network due to smaller vertex degree, and hence, lower implementation cost. In this paper, we present the expression for the diameter of a parallelogramic, honeycomb torus, which extends a known result about rhombic: honeycomb torus. (c) 2005 Elsevier Ltd. All rights reserved.

A novel alternative to cryopreservation for the short-term storage of stem cells for use in cell therapy using alginate encapsulation

Efficient transport of stem/progenitor cells without affecting their survival and function is a key factor in any practical cell-based therapy. However, the current approach using liquid nitrogen for the transfer of stem cells requires a short delivery time window is technically challenging and financially expensive. The present study aims to use semipermeable alginate hydrogels (crosslinked by strontium) to encapsulate, store, and release stem cells, to replace the conventional cryopreservation method for the transport of therapeutic cells within world-wide distribution time frame. Human mesenchymal stem cell (hMSC) and mouse embryonic stem cells (mESCs) were successfully stored inside alginate hydrogels for 5 days under ambient conditions in an air-tight environment (sealed cryovial). Cell viability, of the cells extracted from alginate gel, gave 74% (mESC) and 80% (hMSC) survival rates, which compared favorably to cryopreservation. More importantly, the subsequent proliferation rate and detection of common stem cell markers (both in mRNA and protein level) from hMSCs and mESCs retrieved from alginate hydrogels were also comparable to (if not better than) results gained following cryopreservation. In conclusion, this new and simple application of alginate hydrogel encapsulation may offer a cheap and robust alternative to cryopreservation for the transport and storage of stem cells for both clinical and research purposes.

Rapid, automated detection of stem canker symptoms in woody perennials using artificial neural network analysis

Background Pseudomonas syringae can cause stem necrosis and canker in a wide range of woody species including cherry, plum, peach, horse chestnut and ash. The detection and quantification of lesion progression over time in woody tissues is a key trait for breeders to select upon for resistance. Results In this study a general, rapid and reliable approach to lesion quantification using image recognition and an artificial neural network model was developed. This was applied to screen both the virulence of a range of P. syringae pathovars and the resistance of a set of cherry and plum accessions to bacterial canker. The method developed was more objective than scoring by eye and allowed the detection of putatively resistant plant material for further study. Conclusions Automated image analysis will facilitate rapid screening of material for resistance to bacterial and other phytopathogens, allowing more efficient selection and quantification of resistance responses.

Estimating the diameter of yarns with irregular constituent fibres

Yarn diameter and packing density are difficult to measure directly. Existing models on fibre packing density in a yarn assume that all fibres are uniform and have an identical diameter. Yet real staple yarns, such as wool yarns, consist of fibres of varying diameters. This paper proposes an effective and simple yarn model for calculating the average diameter of yarns, in which fibres have circular cross-section and the close packing in the yarn cross-section. The concept of “area equivalent diameter” is introduced to transform fibres of varying diameters to identical fibres with one equivalent diameter to simplify the calculations of the average yarn diameter for a range of yarns.

The allometric relationship between mean fibre diameter of mohair and the fleece-free liveweight of Angora goats over their lifetime

As mean fibre diameter (MFD) is the primary determinant of mohair price we aimed to quantify the lifetime changes in mohair MFDas Angora goats aged and grew. Measurements were made over 12 shearing periods on a population of Angora goats representing the current range and diversity of genetic origins including South African, Texan and interbred admixtures of these and Australian sources. Records of sire, dam, birthweight, birth parity, liveweight, fleece growth and fleece quality were taken for does and castrated males (wethers) (n = 267 animals). Fleece-free liveweights (FFL_wt) were determined for each goat at shearing time by subtracting the greasy fleece weight from the liveweight recorded immediately before shearing. A restricted maximum likelihood growth curve model was developed for relating MFD to FFL_wt, age and other measurements.Asimple way of describing the results is:MFD= k (FFL_wt)b E; where k is a parameter that can vary in a systematic way with shearing(age), breed, weaning weight, sire, dam and individual; b is a parameter that is the same for nearly the whole study; and E are independent errors from a log-normal distribution. The analysis shows that ^b = 0.34, with s.e. (^b) = 0.021. Thus, mohair MFD was allometrically related to the cube root of FFLwt over the lifetime of Angora goats. However, the allometric proportionality constant differed in a systematic way with age at shearing, genetic strain, weaning weight, sire, dam and individual. For Texan-breed goats, MFD decreased as weaning weight increased (P = 0.00016). The findings indicate that management factors that affect liveweight and weaning weight have lifetime effects on mohair fibre diameter and therefore the value of mohair and the profitability of the mohair enterprise.

Influence of energy and polymer-escapsulated methionine supplements on mohair growth and fibre diameter of Angora goats fed at maintenance

We studied the fleece production of Angora wether goats provided with energy, to maintain liveweight, and polymer-encapsulated methionine while they were fed on poor quality roughage rations in early summer. Forty goats (mean fleece-free liveweight 28.5 kg) were randomly allotted to 5 treatments and housed individually for 12 weeks. The treatments were: control, fed to lose 5 kg liveweight; M, fed to maintain liveweight; and 3 maintenance rations with either 0.5, 1 or 2 g day-1 of polymer-encapsulated methionine. The basal ration was oaten chaff (56.8% digestible dry matter) and all maintenance- fed goats received a supplement of 150 g day- 1 gristed barley. Goats required an estimated 267 kJ ME kg-0.75 day-1 to maintain liveweight. Goats fed the control diet grew less mohair (P<0.05) with reduced mean fibre diameter (P< 0.05) than maintenance-fed goats (4.9 g day-1, 30.0 pm compared with 5.8 g day-1, 31.9 pm). For maintenance-fed animals, the addition of 1 g day- methionine (0.15% of dry matter intake) increased mohair growth by 0.8g day-1 (P<0.075). Feeding barley to prevent liveweight loss and feeding polymer-encapsulated methionine at maintenance is unlikely to result in economic responses in mohair production of goats grazing low quality summer pastures

The age of STEM : educational policy and practice across the world in science, technology, engineering and mathematics

 Across the world STEM (learning and work in Science, Technology, Engineering and Mathematics) has taken central importance in education and the economy in a way that few other disciplines have. STEM competence has become seen as key to higher productivity, technological adaptation and research-based innovation. No area of educational provision has a greater current importance than the STEM disciplines yet there is a surprising dearth of comprehensive and world-wide information about STEM policy, participation, programs and practice.

Effect of diameter of the cotton squares in the development of boll weevil

O objetivo deste trabalho foi estudar o efeito do diâmetro dos botões florais de algodoeiro na massa corporal de adultos do bicudo-do-algodoeiro, Anthonomus grandis Boheman (Coleoptera: Curculionidae). O experimento foi realizado em condições de campo e laboratório, em Jaboticabal (SP), Brasil. Foram realizadas seis amostragens, coletando-se ao acaso dez plantas nas cultivares Coodetec 405 e Fibermax 986, avaliando-se o número e o diâmetro de botões florais. Os botões florais com orifícios de oviposição foram individualizados em frascos e observados diariamente para a visualização da emergência dos adultos. Botões florais com maiores diâmetros proporcionam maior massa corporal de adultos de A. grandis recém-emergidos nas duas cultivares.