Influence of photoperiods on the growth rate and biomass productivity of green microalgae

The effect of different photoperiods: 24 h illumination and a 12:12-h light/dark (12L:12D) cycle on the growth rate and biomass productivity was studied in five algal species: Neochloris conjuncta, Neochloris terrestris, Neochloris texensis, Botryococcus braunii and Scenedesmus obliquus. The green microalgae examined differ in the reproduction mode. Continuous illumination stimulated the growth of B. braunii and S. obliquus more effectively than the growth of the microalgal species from the genus Neochloris. However, under shorter duration of light of the same intensity (12L:12D cycle), the growth of all the three species of Neochloris was stimulated. Under continuous illumination, the specific growth rate in the first phase of B. braunii and S. obliquus cultures was higher than the growth rate of Neochloris, whereas under the 12L:12D cycle, the specific growth rate of all the three Neochloris species was generally higher than that in B. braunii and S. obliquus. As a result, the light regime influenced algal biomass productivity differently. The maximum biomass productivity was obtained in B. braunii and S. obliquus cultures carried out at continuous illumination. All the Neochloris species produced biomass more efficiently at the 12L:12D cycle, which was two–threefold higher than that of B. braunii and S. obliquus. The unicellular species of the green microalgae from the genus Neochloris, examined for the first time in this study, are promising prospective objects for algal biotechnology.     

Muskrat (Ondatra zibethicus) decline after the expansion of American mink (Neovison vison) in Poland

Field survey data in Central Poland revealed that the proportion of sites inhabited by muskrats decreased from 44% to 7% over one decade. This corresponded to the decline in hunting bags of muskrat over the whole of Poland. The largest hunting harvest of muskrat was recorded in 1987/1988 (66,416 individuals), the smallest in 2007/2008 (4,567 individuals). The decline in hunting bags occurred in all regions analysed; however, it was most rapid in the north and north-east. Before the expansion of mink, which started in northern Poland at the beginning of the 1980s, muskrat densities in particular regions depended on the availability of aquatic habitats. A comparison of hunting bags of muskrat and American mink in years 2002–2008 indicated a significant negative correlation between the numbers of these two species harvested in seven regions of Poland. The negative correlation between numbers of muskrat and mink suggests that mink predation is one of the most important factors in the decline of the muskrat population in Poland.     

Calcium transients in the model of rapidly induced anoxic tolerance in rat cortical slices: involvement of NMDA receptors

In this study, we investigated the effects of NMDA receptor antagonists on calcium transients induced by a single 2-min preconditioning anoxia (PA) in rat olfactory cortical slices, and on the ability of PA to prevent pathological calcium overload induced by subsequent 10-min test anoxia (TA). Relative changes in the intracellular Ca(2+) concentration (Ca(i)) and in the level of Ca(2+) bound to intracellular hydrophobic domains (Ca(b)) were monitored using fura-2 and chlortetracycline, respectively. Our results confirmed that TA induces prominent long-lasting increases in Ca(i) and Ca(b), reflecting cellular calcium overload. It was found that PA produces moderate increases in both Ca(2+) pools and prevents Ca(2+) overload induced by TA carried out 90 min later. Calcium transients and the protective effects of PA were significantly suppressed in slices treated with NMDA receptor antagonists during and 30 min after PA. These results indicate that moderate activation of the NMDA receptors participates in the mechanism of the PA-induced anoxic tolerance of cortical neurons.     

Repetitive DNA in and around translocation breakpoints of the Philadelphia chromosome

This paper describes systematic sequence studies of repetitive DNA in and around translocation breakpoints on chromosomes 9 and 22, which are involved in the formation of the Philadelphia chromosome in acute leukemias. In addition to Alu repeats described in previous studies, the breakpoint regions appear to contain many other repetitive elements, including a member of a new repetitive family (MER34) reported in this paper. Identification of these repeats broadens current studies on the possible involvement of repetitive DNA in this intensely studied chromosomal translocation.     

Telocytes: new insight into the pathogenesis of gallstone disease

The major mechanisms of gallstone formation include biliary cholesterol hypersecretion, supersaturation and crystallization, mucus hypersecretion, gel formation and bile stasis. Gallbladder hypomotility seems to be a key event that triggers the precipitation of cholesterol microcrystals from supersaturated lithogenic bile. Telocytes, a new type of interstitial cells, have been recently identified in many organs, including gallbladder. Considering telocyte functions, it is presumed that these cells might be involved in the signalling processes. The purpose of this study was to correlate the quantity of telocytes in the gallbladder with the lithogenicity of bile. Gallbladder specimens were collected from 24 patients who underwent elective laparoscopic cholecystectomy for symptomatic gallstone disease. The control group consisted of 25 consecutive patients who received elective treatment for pancreatic head tumours. Telocytes were visualized in paraffin sections of gallbladders with double immunofluorescence using primary antibodies against c‐Kit (anti‐CD117) and anti‐mast cell tryptase. Cholesterol, phospholipid and bile acid levels were measured in gallbladder bile. The number of telocytes in the gallbladder wall was significantly lower in the study group than that in the control group (3.03 ± 1.43 versus 6.34 ± 1.66 cell/field of view in the muscularis propria, P < 0.001) and correlated with a significant increase in the cholesterol saturation index. The glycocholic and taurocholic acid levels were significantly elevated in the control subjects compared with the study group. The results suggest that bile composition may play an important role in the reduction in telocytes density in the gallbladder.     

Theoretical ab Initio Study of the Effects of Methylation on Structure and Stability of G:C Watson-Crick Base Pair

Abstract

Methylation of DNA occurs most readily at N(3), N(7), and O(6) of purine bases and N(3) and O(2) of pyrimidines. Methylated bases are continuously formed through endogenous and exogenous mechanisms. The results of a theoretical ab initio study on the methylation of G:C base pair components are reported. The geometries of the local minima were optimized without symmetry restrictions by the gradient procedure at DFT level of theory and were verified by energy second derivative calculations. The standard 6–31G(d) basis set was used. The single-point calculations have been performed at the MP2/6–31G(d,p), MP2/6–31₊₊G(d,p), and MP2/6–311₊₊G(2d,2p) levels of theory. The geometrical parameters, relative stability and counterpoise corrected interaction energies are reported. Also, using a variation-perturbation energy decomposition scheme we have found the vital contributions to the total interaction energy.     

Laser interferometry analysis of ciprofloxacin and ampicillin diffusion from liposomal solutions to water phase

The paper presents experimental investigations of diffusion of antibiotics (ciprofloxacin or ampicillin) into the water phase from mixtures of neutral or negatively charged liposomes, and antibiotic–liposome interactions. Using the laser interferometry technique, the amounts and fluxes of released antibiotics, concentration field evolution, and the velocity of the concentration boundary layer’s “growth” were determined. To avoid the limitations of membranes, a measurement system without the artificial boundary of phases with a free water–solution interface has been proposed. It was found that the diffusion of anionic and neutral liposomes into the water phase was insignificant and mainly the diffusion of antibiotics was measured. Differences in the diffusion kinetics of ciprofloxacin and ampicillin from liposomal solutions to the water phase were observed. Ampicillin diffused more efficiently than ciprofloxacin regardless of the liposomal solution type. Moreover, the amount of ampicillin and ciprofloxacin released from the anionic liposomal phase was higher than that from the neutral one. Our results confirm that ciprofloxacin at neutral pH shows little tendency to bind neutral liposomes. Additionally, it was also observed that ciprofloxacin disrupts negatively charged liposomes as a final effect of antibiotic–lipid interactions.     

Metabolic signature associated with parameters of the complete blood count in apparently healthy individuals

Metabolomics studies now approach large sample sizes and the health characterization of the study population often include complete blood count (CBC) results. Upon careful interpretation the CBC aids diagnosis and provides insight into the health status of the patient within a clinical setting. Uncovering metabolic signatures associated with parameters of the CBC in apparently healthy individuals may facilitate interpretation of metabolomics studies in general and related to diseases. For this purpose 879 subjects from the population‐based Study of Health in Pomerania (SHIP)‐TREND were included. Using metabolomics data resulting from mass‐spectrometry based measurements in plasma samples associations of specific CBC parameters with metabolites were determined by linear regression models. In total, 118 metabolites significantly associated with at least one of the CBC parameters. Strongest associations were observed with metabolites of heme degradation and energy production/consumption. Inverse association seen with mean corpuscular volume and mean corpuscular haemoglobin comprised metabolites potentially related to kidney function. The presently identified metabolic signatures are likely derived from the general function and formation/elimination of blood cells. The wealth of associated metabolites strongly argues to consider CBC in the interpretation of metabolomics studies, in particular if mutual effects on those parameters by the disease of interest are known.     

Interactions between the endoplasmic reticulum, mitochondria, plasma membrane and other subcellular organelles

Several recent works show structurally and functionally dynamic contacts between mitochondria, the plasma membrane, the endoplasmic reticulum, and other subcellular organelles. Many cellular processes require proper cooperation between the plasma membrane, the nucleus and subcellular vesicular/tubular networks such as mitochondria and the endoplasmic reticulum. It has been suggested that such contacts are crucial for the synthesis and intracellular transport of phospholipids as well as for intracellular Ca²⁺ homeostasis, controlling fundamental processes like motility and contraction, secretion, cell growth, proliferation and apoptosis. Close contacts between smooth sub-domains of the endoplasmic reticulum and mitochondria have been shown to be required also for maintaining mitochondrial structure. The overall distance between the associating organelle membranes as quantified by electron microscopy is small enough to allow contact formation by proteins present on their surfaces, allowing and regulating their interactions. In this review we give a historical overview of studies on organelle interactions, and summarize the present knowledge and hypotheses concerning their regulation and (patho)physiological consequences.