Telomerase as a “stemness” enzyme

Pluripotent or multipotent stem cells are involved in development and tissue homeostasis;they have the ability to self-renew and differentiate into various types of functional cells.To maintain these properties,stem cells must undergo sustained or unlimited proliferation that requires the stabilization of telomeres,which are essential for chromosome end protection.Telomerase,an RNA-dependent DNA polymerase,synthesizes telomeric DNA.Through the lengthening of telomeres the lifespans of cells are extended,or indefinite proliferation is conferred;this is intimately associated with stem cell phenotype.This review highlights our current understanding of telomerase as a"stemness"enzyme and discusses the underlying implications.     

Rubyspot Territorial Damselflies Behave as “Nasty Neighbors”

Two mutually-excluding hypotheses explain the intensity of aggression between neighbors and their non-neighbors in territorial animals. On one hand, the “dear enemy” hypothesis predicts that territorial animals should be more tolerant towards their neighbors than towards non-neighbors. Conversely, the “nasty neighbor” hypothesis predicts increased aggression towards neighbors than non-neighbors. These different situations depend on who is more likely to be a real competitor, either a neighbor or a non-neighbor, and the intensity of resource competition. Male damselfly of Hetaerina vulnerata defend riverine, mating territories that is the main way to have access to females. These territories are not fixed and so males continuously defend them especially against neighbors. Given this, we tested whether the nasty neighbor principle operates in this species. We monitored a population during an entire mating season, and recorded duration of aggressive behaviors. As a key prediction of the nasty neighbor hypothesis, we expected that such behaviors last for longer when encountering a conspecific neighbor than a conspecific non-neighbor. We also predicted that such duration should be date-dependent as territorial competition could increase in the middle of the season when male density is at its highest. Our results corroborated that aggressive behaviors lasted longer against a neighbor male than a non-neighbor male but there was not effect of date. Thus, neighbors may pose a greater risk and may be a strong selective force than non-neighbors in terms of resource competition. Since neighbor males are continuously trying to widen their territory boundaries (a situation that has been also found in other study systems), an owner male may not even need to recognize his neighbors to fight back.     

“Nojirimycin” as a Potent Inhibitor of Glucosidase

Glucose-6-phosphate dehydrogenase in a yeast, Hansenula mrakii IFO 0895 is induced when the cells are cultured in a medium containing lipid hydroperoxide. The enzyme was purified from H. mrakii to the homogeneous state on polyacrylamide gel electrophoresis. The molecular weight of the purified enzyme was estimated to be approximately 52kDa by SDS-PAGE and 130 kDa by Sephadex G-150column chromatography, respectively. The enzyme was specific to glucose-6-phosphate and NADP⁺, and K_mvalues for glucose-6-phosphate and NADP⁺ were 293µM and 24.1 µM, respectively. The enzyme activity was inhibited by diethylpyrocarbonate and 2, 4, 6-trinitrobenzene sulfonate, and by metal ions such as Zn^{2 +}, Cd^{2 +}, Cu^{2 +}, and Al^{3 +} . tert-Butyl hydroperoxide, a kind of lipid hydroperoxide, slightly(approximately 20%) increased the enzyme activity.     

The “Artificial Artery” as In Vitro Perfusion Model

Metabolic stimuli, pressure, and fluid shear stress (FSS) are major mediators of vascular plasticity. The exposure of the vessel wall to increased laminar FSS is the main trigger of arteriogenesis, the remodelling of pre-existent arterio-arteriolar anastomoses to functional conductance arteries. In this study, we have used an in vitro bioreactor to investigate cell-specific interactions, molecular mechanisms as well as time-dependent effects under laminar FSS conditions. This bioreactor termed “artificial artery” can be used for screening potential arterio-protective substances, pro-arteriogenic factors, and for investigating biomarkers of cardiovascular diseases such as cardiac diseases. The bioreactor is built up out of 14 hollow fiber membranes colonized with endothelial cells (HUVECs) on the inside and smooth muscle cells (HUASMCs) on the outside. By means of Hoechst 33342 staining as well as immunocytochemistry of ß-catenin and α-smooth-muscle-actin, a microporous polypropylene membrane was characterized as being the appropriate polymer for co-colonization. Defined arterial flow conditions (0.1 N/m2 and 3 N/m2), metabolic exchange, and cross-talk of HUVECs and HUASMCs through hollow fibers mimic physiological in vivo conditions of the vasculature. Analysing mono- and co-culture secretomes by MALDI-TOF-TOF mass spectrometry, we could show that HUVECs secreted Up4A upon 3 N/m2. A constant cellular secretion of randomly chosen peptides verified viability of the “artificial artery” for a cultivation period up to five days. qRT-PCR analyses revealed an up-regulation of KLF2 and TIMP1 as mechano-regulated genes and demonstrated arterio-protective, homeostatic FSS conditions by a down-regulation of EDN1. Expression analyses of VWF and EDN1 furthermore confirmed that RNA of both cell types could separately be isolated without cross-contamination. CCND1 mRNA expression in HUVECs did not change upon FSS indicating a quiescent endothelial phenotype. Taken together, the “artificial artery” provides a solid in vitro model to test pharmacological active compounds for their impact on arterio-damaging or arterio-protective properties on vascular response.     

Why “Sudden Appearance” Is Not as It Appears

Recent action taken by the Texas State Board of Education has opened the door to the inclusion of creationist arguments into public school science curriculum in that state and—because of the critical role of Texas in textbook adoptions—perhaps in many other states as well. One of the arguments that have been targeted by creationists is the “sudden appearance” of animal phyla at the base of the Cambrian period (i.e., the Cambrian explosion). While the creationist argument is both misleading and deeply flawed, high school biology teachers are often lacking the relevant paleontological knowledge to refute the argument. This paper attempts to provide teachers with a set of core counterpoints to the creationists’ claims along with a list of online resources that are highly visual in nature and should provide the means to help stimulate genuine student critical thinking about this issue, an alleged goal of the creationist agenda.     

Comments on “Seed germination as a thermobiological problem”

Summary In the above mentioned article [1] the notion of a time-dependent Gibbs free energy has been introduced to explain the observed time-pattern of embryo growth in seeds. Furthermore, the notion of a non-random thermal communication has been inferred from an inspection of the shapes of germination time distributions. It can be shown, however, that the reasoning leading to the time-dependent thermodynamic potential is based on inappropriate interpretation of kinetic equations, and that the shape of the distributions of germination time might be a natural consequence of the initial distribution of embryo size in the seeds.Discussion about the Paper Seed Germination as a Thermobiological Problem by L. G. Labouriau Radiation and Environmental Biophysics 15:345–366 (1978)     

“Make Everything as Simple as Possible,But Not Simpler”: A Simple Approach is as Good as a Complex Algorithm for Insulin Dose Self-Adjustment

Abbreviations:A1c = glycated hemoglobin A1cDM2 = type 2 diabetes mellitusRCT = randomized controlled trialSMBG = self-monitoring blood glucose     

A spotlight on “established”, as opposed to “newcomer”, Americans

By elaborating upon the idea of “relational assimilation”, Tomas Jimenez alters the dominant lens through which social scientists, and especially sociologists, have understood the concept of assimilation and the effects of immigration. In this highly readable and thoughtful book, we are asked to conceive of this kind of assimilation as one which involves “the give-and-take of adjustment”, not just a one-way route by which “newcomers” must adapt to settings populated by “established” members of the population. According to the author, ongoing forms of immigration and its resulting diversity actually change the regional self-understandings of those who are already living in those settings.     

Leslie matrix models as “stroboscopic snapshots” of McKendrick PDE models

 High dimensional Leslie matrix models have long been viewed as discretizations of McKendrick PDE models. However, these two fundamental classes of models can be linked in a completely different way. For populations with periodic birth pulses, Leslie models of any dimension can be viewed as “stroboscopic snapshots” (in time) of an associated impulsive McKendrick model; that is, the solution of the discrete model matches the solution of the corresponding continuous model at every discrete time step. In application, McKendrick models of populations with birth pulses can be used to identify the state of the population between the discrete census times of the associated Leslie model. Furthermore, McKendrick models describing populations with near-synchronous birth pulses can be viewed as realistic perturbations of the associated Leslie model. Received: 7 August 1997 / Revised version: 15 January 1998     

Evaluation of “sequence-tagged-site” PCR products as molecular markers in wheat

The polymerase chain reaction (PCR) is an attractive technique for many genome mapping and characterization projects. One PCR approach which has been evaluated involves the use of randomly amplified polymorphic DNA (RAPD). An alternative to RAPDs is the sequence-tagged-site (STS) approach, whereby PCR primers are designed from mapped low-copy-number sequences. In this study, we sequenced and designed primers from 22 wheat RFLP clones in addition to testing 15 primer sets that had been previously used to amplify DNA sequences in the barley genome. Our results indicated that most of the primers amplified sequences that mapped to the expected chromosomes in wheat. Additionally, 9 of 16 primer sets tested revealed polymorphisms among 20 hexaploid wheat genotypes when PCR products were digested with restriction enzymes. These results suggest that the STS-based PCR analysis will be useful for generation of informative molecular markers in hexaploid wheat.Contribution no. J-2833 of the Montana Agric Exp Stn     

Salinity optima as affected by temperature for some “Usar” soil aspergilli

Studies on the effect of two integrated factors viz; temperature and salinity on the growth of certain Usar soil Aspergilli have shown that as the temperature of incubation increases, the salinity optima also increases until the temperature becomes the limiting factor.     

General base-catalyzed ester hydrolysis as a model of the “charge-relay” system

The validity of the “charge-relay” system in serine esterases was examined by use of the general base-catalyzed hydrolysis of ethyl chloroacetate (I) as a model system. The general base catalytic rate for 2-benzimidazoleacetic acid (II) exhibited an eightfold positive deviation from the Brønsted plot including benzimidazole, imidazole, N-methylimidazole (V), and acetate ion, though in nucleophilic catalysis of the hydrolysis of p-nitrophenyl acetate, the point for II conformed to the Brønsted relationship together with imidazole and benzimidazole derivatives. The positive deviation of II from the Brønsted plot for the general base-catalysis was attributed to the cooperativity of the carboxyl group of II, the imidazolyl group of II, and the hydroxyl group of water. The present result provides support for the “charge-relay” system. Furthermore, the (essentially) total loss of the enzymatic activity due to N-3 methylation of histidine-57 in α-chymotrypsin is discussed in comparison to the general base-catalysis of V in the hydrolysis of I, which is also favorable for the “charge-relay” system.     

Hürthle cell Thyroid Carcinoma Presenting as A “Hot” Nodule

ObjectiveTo report an unusual clinical scenario and a rare histopathologic finding of Hürthle cell thyroid carcinoma in a patient with an autonomous thyroid nodule.MethodsWe describe the presentation and clinical course leading to the surprising histopathologic diagnosis of Hürthle cell carcinoma in a pediatric patient who was diagnosed with hyperthyroidism presenting as a solitary toxic nodule.ResultsA 13-year-old white girl presented with a recent history of a palpable thyroid nodule during a routine primary care clinic visit. She was asymptomatic, and thyroid function tests revealed a suppressed thyrotropin concentration, high-normal free thyroxine concentration, and elevated triiodothyronine concentration. The patient underwent dedicated thyroid ultrasonography revealing a 3.5-cm complex mass in the left lobe with increased central vascularity. Iodine 123 imaging of the thyroid demonstrated homogenous, hyperintense activity in the left lobe. The right lobe was not visualized. A solitary toxic nodule was diagnosed, and, considering her age, she was referred for surgical management. The patient underwent a left lobectomy with isthmusectomy. Pathologic examination revealed a 5-cm, encapsulated, well-differentiated Hürthle cell carcinoma with negative margins and no lymphovascular invasion. The patient underwent subsequent completion thyroidectomy with no evidence of residual carcinoma in the right thyroid lobe.ConclusionsMalignancy in autonomously functioning thyroid nodules is rare. Most of the thyroid nodules presenting as “hot” on radioiodine scintigraphy are benign follicular adenomas. However, this case represents a rare clinical entity, and it highlights the need for clinicians to be vigilant and aware that occasionally carcinomas can masquerade as scintigraphic “hot” nodules. (Endocr Pract. 2011;17:e68-e72)     

Maintenance of function without selection:Alu sequences as “Cheap Genes”

Summary Continued insertion into the genome of functionalAlu sequences is expected to compensate for the functional eclipse of older sequences attributable to structural adulteration and can be presumed to establish a renewable store of functional sequences at a relatively elevated numerical level. This store of functional sequences could be maintained at almost no selective cost. A strategy of maintaining function in multiple sequence copies with selection limited to a very few master (source) sequences may be resorted to also by other types of DNA sequences that are generated repeatedly during evolution and that are spread over many sectors of the genome.     

Future Ecological Risk Assessment: “Status Humana,” Man as the Measure

The current environmental paradigm of attempting to maintain, to the extent possible, the “status quo” is intellectually dishonest and untenable. Man has long been at least implicitly recognized as “the measure of all things.” Ecological risk assessments (ERAs) need to be based on the reality that humans have primacy in nature and are a major evolutionary force, albeit a selfish one: the “status humana” paradigm. A variety of facts are set out in support of this paradigm and to demonstrate both its relevance and its value. Examples of applications of this paradigm include hormesis, chemicals, food production and biodiversity, socioeconomic and environmental issues, ecotoxicology and bioavailability, introduced species, and environmental relevance.