Na-NMR Studies of the Intracellular Sodium Ion Concentration in the Halotolerant Alga Dunaliella salina

The Intracellular Na⁺ concentration in the halotolerant alga Dunaliella salina was measured in intact cells by ²³Na-NMR spectroscopy, utilizing the dysprosium tripolyphosphate complex as a sodium shift reagent, and was found to be 88 ± 28 millimolar. Intracellular sodium ion content and intracellular volume were the same, within the experimental error, in cells adapted to grow in media containing between 0.1 and 4.0 molar NaCl. These values assume extracellular and intracellular NMR visibilities of the ²³Na nuclei of 100 and 40%, respectively. The relaxation rate of intracellular sodium was enhanced with increasing salinity of the growth medium, in parallel to the intracellular osmosity due to the presence of glycerol, indicating that Na⁺ ions and glycerol are codistribbuted within the cell volume.     

Urea tolerance and osmoregulation in Bufo viridis and Rana ridibunda

1. The tolerance and adaptation to urea solutions by terrestrial green toads (Bufo viridis) and semi-aquatic frogs (Rana Ridibunda) were studied. 2. the green toad showed tolerance to urea solution of 800 mM and the frogs showed tolerance only to about 400 mM urea solution. 3. The plasma concentrations of both species was hyperosmotic to the external medium in all the different urea solutions. 4. Blood osmolality, urea, Na+ and Cl- concentrations of B. viridis were always higher than in R. ridibunda. 5. The urea concentration in muscle of R. ridibunda was higher than the urea concentration in muscle of B. viridis. 6. The muscle tissue weight loss of B. viridis was significantly lower than R. ridibunda.     

Effect of 17β-estradiol on calcium response to phytohaemagglutinin in human lymphocytes

Pre-treatment of human lymphocytes with 17-estradiol diminishes the increase in concentration of cytosolic free calcium after stimulation with phytohaemagglutinin. The effect is dependent on 17-estradiol concentration and on the preincubation time. The effect is not due to an interaction between 17-estradiol and phytohaemagglutinin, but appears to be a consequence of the binding of the hormone to the cell surface. The effect is specific for 17-estradiol, since the isomer and other steroid hormones (progesterone, testosterone, diethylstilbestrol and 5-androstan), have no effect. Since the effect of the 17-estradiol can be suppressed by treatment of lymphocytes with ouabain, it appears that the effect of estradiol on the rise of cytosolic calcium induced by phytohaemagglutinin is mediated by the (Na, K)-ATPase.     

Metabolic studies with NMR spectroscopy of the alga Dunaliella salina trapped within agarose beads

A technique for the entrapment of the unicellular algae Dunaliella salina in agarose beads and their perfusion during NMR measurements is presented. The trapped cells maintained their ability to proliferate under normal growth conditions, and remained viable and stable under steady-state conditions for long periods during NMR measurements. Following osmotic shock in the dark, prominent changes were observed in the intracellular level of ATP and polyphosphates, but little to no changes in the intracellular pH or orthoposphate content. When cells were subjected to hyperosmotic shock, the ATP level decreased. The content of NMR-visible polyphosphates decreased as well, presumably due to the production of longer, NMR-invisible structures. Following hypoosmotic shock, the ATP content increased and longer polyphosphates were broken down to shorter, more mobile polymers.     

Alignment free identification of clones in B cell receptor repertoires

Following antigenic challenge, activated B cells rapidly expand and undergo somatic hypermutation, yielding groups of clonally related B cells with diversified immunoglobulin receptors. Inference of clonal relationships based on the receptor sequence is an essential step in many adaptive immune receptor repertoire sequencing studies. These relationships are typically identified by a multi-step process that involves: (i) grouping sequences based on shared V and J gene assignments, and junction lengths and (ii) clustering these sequences using a junction-based distance. However, this approach is sensitive to the initial gene assignments, which are error-prone, and fails to identify clonal relatives whose junction length has changed through accumulation of indels. Through defining a translation-invariant feature space in which we cluster the sequences, we develop an alignment free clonal identification method that does not require gene assignments and is not restricted to a fixed junction length. This alignment free approach has higher sensitivity compared to a typical junction-based distance method without loss of specificity and PPV. While the alignment free procedure identifies clones that are broadly consistent with the junction-based distance method, it also identifies clones with characteristics (multiple V or J gene assignments or junction lengths) that are not detectable with the junction-based distance method.     

Ethnic groups and high sensitivity C-reactive protein in Israel

Abstract

High-sensitivity C-reactive protein (hs-CRP) is a biomarker that correlates with atherothrombotic risk and outcome. hs-CRP is influenced by various modifiable and non-modifiable factors. We studied the relationship between ethnic background and hs-CRP level, among the Jewish population in Israel. A total of 3659 men and 2180 women were divided into two ethnic groups (Ashkenazi and Sephardic Jews), based on the knowledge of Jewish immigration patterns throughout the centuries. Mean hs-CRP levels were calculated for each group and were adjusted for various factors known to influence hs-CRP. Sephardic Jews were found to have higher adjusted mean hs-CRP levels (2.0 mg l^?1 for men and 3.9 mg l^?1 for women) compared with Ashkenazi Jews (1.5 mg l^?1 for men and 2.9 mg l^?1 for women). Ethnic background emerged as an independent significant predictor of hs-CRP levels. We demonstrated that ethnicity is an important factor when considering hs-CRP as a marker of atherothrombotic risk.     

Interference with gene expression induces rapid apoptosis in p53-null T lymphoma cells

Two p53-null T lymphoma cell lines proved to be highly sensitive to inhibition of gene expression. With either actinomycin D or cycloheximide, apoptosis commenced within 2 h, as indicated by loss of membrane integrity, degradation of certain proteins (including the phosphatase calcineurin) and DNA fragmentation. These effects were ablated by co-expression of Bcl-2 or co-incubation with the caspase inhibitor Z-VAD-fmk. These results suggest that the apoptotic machinery is in place in these cells but held in check by an unknown labile protein, which probably acts upstream of Bcl-2. Although cycloheximide can activate the JNK or p38 MAP kinases in some cells, neither was implicated here. However, disruption of phosphoinositide 3-kinase signaling may be involved, because the cells were also sensitive to wortmannin. The high sensitivity of the p53-null lymphoma cells to inhibitors of gene expression suggests that such inhibitors might prove useful in the cytotoxic therapy of certain tumors.     

Cloning of European eel (Anguilla anguilla) FSH-beta subunit, and expression of FSH-beta and LH-beta in males and females after sex determination

The European eel (Anguilla anguilla) is a catadromic teleost species with a complex life cycle, both in sea and freshwater environments. The sex determination phase of gonadal development occurs in a freshwater environment. Polymorphism occurs in increasing rates with respect to gender. While males stop growing at approximately 150 g, females continue to grow to being much larger. In this study, we cloned the cDNA FSH-beta subunit of the European eel (A. anguilla), and measured the mRNA levels of FSH-beta and LH-beta in males and females after sex determination. The FSH-beta subunit cDNA consisted of 1068 bp, encoding a 127 amino acid peptide. A comparison between European and Japanese eels of the FSH-beta amino acid sequence showed 98% similarity.