Ultrastructure of the body cavities in Phylactolaemata (Bryozoa)

Only species belonging to the bryozoan subtaxon Phylactolaemata possess an epistome. To test whether there is a specific coelomic cavity inside the epistome, Fredericella sultana, Plumatella emarginata, and Lophopus crystallinus were studied on the ultrastructural level. In F. sultana and P. emarginata, the epistome contains a coelomic cavity. The cavity is confluent with the trunk coelom and lined by peritoneal and myoepithelial cells. The lophophore coelom extends into the tentacles and is connected to the trunk coelom by two weakly ciliated coelomic ducts on either side of the rectum. The lophophore coelom passes the epistome coelom on its anterior side. This region has traditionally been called the forked canal and hypothesized to represent the site of excretion. L. crystallinus lacks an epistome. It has a simple ciliated field where an epistome is situated in the other species. Underneath this field, the forked canal is situated. Compared with the other species, it is pronounced and exhibits a dense ciliation. Despite the occurrence of podocytes, which are prerequisites for a selected fluid transfer, there is no indication for an excretory function of the forked canal, especially as no excretory porus was found. J. Morphol. 2009. © 2008 Wiley‐Liss, Inc.     

Generation of Mini-Tn10 transposon insertion mutant library of Bacillus thuringiensis for the investigation of genes required for its bacteriocin production

Bacillus thuringiensis strain BUPM4 is known for its ability to produce a bacteriocin, called Bacthuricin F4 (BF4), which inhibits the growth of several Gram-positive bacteria and particularly Bacillaceae . This study aimed to use the insertional transposon mutagenesis approach for disrupting and thus identifying genes associated with BF4 synthesis. Here, the mini-Tn 10 transposon was used to generate a library of B. thuringiensis mutants. Twenty thousand clones were screened for the search of mutants with affected bacteriocin synthesis. By molecular hybridization, it was demonstrated that the mini-Tn 10 transposition occurred in different sites. Clone MB1, containing a mini-Tn 10 single-copy insertion, lost the BF4 synthesis, but maintained its immunity to BF4. The flanking sequences surrounding the mini-Tn 10 insertion were cloned and sequenced. Homology searches of the surrounding ORFs revealed a strong similarity to a phage tail component, which allowed us to postulate that BUPM4 bacteriocin could be a phage tail-like one.     

The (palaeo) environmental significance of modern calcareous dinoflagellate cysts: a review

Increased interest in the environmental applicability of calcareous dinoflagellate cysts for palaeo-environmental studies arose in the last two decades, when it was discovered that they constitute a widespread and abundant group within the calcareous phytoplankton. As primary producers they are directly influenced by environmental Parameters of the surrounding water masses, and therefore extremely suitable for detailed palaeo-environmental and -oceanographical reconstructions. During the last years, detailed investigations on their distribution in surface sediments of the South Atlantic Ocean, the Mediterranean Sea and the Arabian Sea were carried out, in order to reveal which environmental parameters influence their distribution. This, in turn, formed the base for palaeo-environmental and -oceanographical reconstructions. The compilation of the available data on calcareous dinoflagellate ecology, morphology, taxonomy and palaeo-environmental application presented here demonstrates their ample application potential as palaeo-environmental tools.      

Improvement of ethyl glucuronide determination in human urine and serum samples by solid-phase extraction

An improved method for the determination of ethyl glucuronide (EtG) in human serum and urine was developed using solid-phase extraction (SPE) and gas chromatography (GC) with mass spectrometric detection (MS). EtG was isolated from serum and urine using aminopropyl SPE columns after deproteination with perchloric acid and hydrochloric acid, respectively. The chromatographic separation was performed on a DB 1701 fused-silica column. At a signal-to-noise ratio of 3:1, a quantification limit of 173 and 560 ng/ml and a detection limit of 37 and 168 ng/ml could be determined for serum and urine, respectively. This indicates high specificity and sensitivity of the described method. The mean absolute recovery was 85%, while intra- and inter-day precision of the assay were all less than 7.5%. The linearity of the calibration curves was satisfying as indicated by correlation coefficients of >0.993. The presented method provides the basis for determination and identification of EtG in human serum and urine samples in a low-concentration range for monitoring alcohol consumption during treatment for alcohol dependence and comorbid alcohol abuse of psychotherapy patients.     

Effects of wheel running on photoperiodic responses of Djungarian hamsters (Phodopus sungorus)

Djungarian hamsters (Phodopus sungorus) were exposed to artificial short days either with access to a running wheel (RW) or without. Within 6 weeks RW hamsters considerably increased their body mass, whereas controls showed the typical body mass reduction. Estimation of paired testis weights indicated a decelerated testis regression in RW hamsters. Subsequent locking of RWs for 9 weeks led to a decline in body mass of RW animals in parallel to controls. Daily torpor was almost completely missing in hamsters with initially unlocked wheels. During the final phase when RWs were again unlocked (3 weeks), body mass of exercising hamsters increased again, while controls reached the nadir in body mass. In comparison to equiponderate long-day (LD) controls the relative liver weight of RW hamsters was significantly increased unlike the relative heart weight. However, the latter tended to be higher than in sedentary LD hamsters. A growth-stimulating effect of wheel running was proven by elongated femora in exercising short-day (SD) hamsters compared to SD controls and suggested by exercise-induced elevation of body mass in a further experiment under continuous LD conditions, indicating a growth-promoting effect of wheel running independent from the photoperiod.     

Molecular and immunological characterization of a wheat serine proteinase inhibitor as a novel allergen in baker's asthma

IgE-mediated sensitization to wheat flour belongs to the most frequent causes of occupational asthma. A cDNA library from wheat seeds was constructed and screened with serum IgE from baker's asthma patients. One IgE-reactive phage clone contained a full-length cDNA coding for an allergen with a molecular mass of 9.9 kDa and an isoelectric point of 6. According to sequence analysis it represents a member of the potato inhibitor I family, a group of serine proteinase inhibitors, and thus is the first allergen belonging to the group 6 pathogenesis-related proteins. The recombinant wheat seed proteinase inhibitor was expressed in Escherichia coli and purified to homogeneity. According to circular dichroism analysis, it represented a soluble and folded protein with high thermal stability containing mainly beta-sheets, random coils, and an alpha-helical element. The recombinant allergen showed allergenic activity in basophil histamine release assays and reacted specifically with IgE from 3 of 22 baker's asthma patients, but not with IgE from grass pollen allergic patients or patients suffering from food allergy to wheat. Allergen-specific Abs were raised to localize the allergen by immunogold electron microscopy in the starchy endosperm and the aleuron layer. The allergen is mainly expressed in mature wheat seeds and, despite an approximately 50% sequence identity, showed no relevant cross-reactivity with allergens from other plant-derived food sources such as maize, rice, beans, or potatoes. Recombinant wheat serine proteinase inhibitor, when used in combination with other specific allergens, may be useful for the diagnosis and therapy of IgE-mediated baker's asthma.     

FtsZ bacterial cytoskeletal polymers on curved surfaces: the importance of lateral interactions

A recent theoretical article provided a mechanical explanation for the formation of cytoskeletal rings and helices in bacteria assuming that these shapes arise, at least in part, from the interaction of the inherent mechanical properties of the protein polymers and the constraints imposed by the curved cell membrane (Andrews, S., and A. P. Arkin. 2007. Biophys. J. 93:1872-1884). Due to the lack of experimental data regarding the bending rigidity and preferential bond angles of bacterial polymers, the authors explored their model over wide ranges of preferred curvature values. In this letter, we present the shape diagram of the FtsZ bacterial polymer on a curved surface but now including recent experimental data on the in vitro formed FtsZ polymers. The lateral interactions between filaments observed experimentally change qualitatively the shape diagram and indicate that the formation of rings over spirals is more energetically favored than estimated in the above-mentioned article.     

Increased production of the ether-lipid platelet-activating factor in intestinal epithelial cells infected by Salmonella enteritidis

When exposed to enteric pathogens intestinal epithelial cells produce several cytokines and other proinflammatory mediators. To date there is no evidence that the ether-lipid platelet-activating factor (PAF) is one of these mediators. Our results revealed a significant increase in PAF production by human colonic tissue 4 h after infection by enterohemorrhagic Escherichia coli (EHEC) or Salmonella enteritidis. PAF is produced in the gut by cells of the immune system in response to bacterial infection. To determine whether the epithelial cells of colonic mucosa might also modulate PAF levels, we carried out PAF quantification and analysis of the enzymes involved in PAF synthesis in 5-day-old (undifferentiated) or 28-day-old (differentiated) Caco-2 cell cultures. Infection of undifferentiated Caco-2 cells with either bacterium had no effect on PAF levels, whereas in differentiated cells, infection by S. enteritidis increased PAF levels. Following infection by S. enteritidis, there were no changes in the activity of dithiothreitol-insensitive choline phosphotransferase. However, the enzymes of the remodeling pathway cytosolic phospholipase A(2), which catalyzes the formation of the PAF precursor lysoPAF, and lysoPAF acetyltransferase, are activated in the infected epithelial cells. This response is Ca(2+)-dependent.     

Prevalence of metabolic syndrome in the interior of Croatia: the Baranja region

Metabolic syndrome (MS), a constellation of metabolic risk factors associated with development of cardiovascular diseases and Type 2 diabetes (T2D), has emerged as a public health problem of enormous proportions in developed and developing countries. We have reported previously its prevalence in several island populations of the Eastern Adriatic coast of Croatia. In spite of leading a relatively traditional life style pattern including adherence to a Mediterranean diet, the prevalence of MS in these populations is high and comparable to that in developed nations. However, data on prevalence of MS among the mainland Croatian populations is limited. Therefore, we conducted a study in an outbred population comprising of Croats, Hungarians and Serbs from the Baranja region of mainland Croatia. Although this is an ethnically heterogeneous population, the constituent groups exchange mates and therefore, are not reproductively isolated. The life style patterns are also similar. Overall prevalence of MS, assessed by the National Cholesterol Education Program (NCEP) criteria, is 40% (35% in males and 42% in females) with Body Mass Index (BMI) as the predictor of obesity and 42% (52% in males and 39% in females) with Waist Hip Ratio (WHR) as the predictor of obesity. It is likely that, in addition to genetic risk factors, a host of environmental factors that include dietary habits and relatively urban life style in a modernized society have influenced the levels of the constituent metabolic traits leading to an increased prevalence of MS.     

Dysregulation of dopamine-dependent mechanisms as a determinant of hypertension: studies in dopamine receptor knockout mice

Dopamine plays an important role in the pathogenesis of hypertension by regulating epithelial sodium transport and by interacting with vasoactive hormones/humoral factors, such as aldosterone, angiotensin, catecholamines, endothelin, oxytocin, prolactin pro-opiomelancortin, reactive oxygen species, renin, and vasopressin. Dopamine receptors are classified into D(1)-like (D(1) and D(5)) and D(2)-like (D(2), D(3), and D(4)) subtypes based on their structure and pharmacology. In recent years, mice deficient in one or more of the five dopamine receptor subtypes have been generated, leading to a better understanding of the physiological role of each of the dopamine receptor subtypes. This review summarizes the results from studies of various dopamine receptor mutant mice on the role of individual dopamine receptor subtypes and their interactions with other G protein-coupled receptors in the regulation of blood pressure.