Identification and Molecular Characterization of Homeologous Δ9-Stearoyl Acyl Carrier Protein Desaturase 3 Genes from the Allotetraploid Peanut (Arachis hypogaea)

The stearoyl–acyl carrier protein (ACP) desaturase (SAD) is a nuclear-encoded, plastid-localized soluble desaturase that catalyzes the conversion of stearoyl-ACP to oleoyl-ACP and plays a key role in the determination of the properties of the majority of cellular glycerolipids. Sad genes from a variety of plant species have been cloned and characterized. However, in peanut (Arachis hypogaea), an important edible and oilseed crop, these genes have not yet been characterized. By searching peanut expressed sequence tag (EST) and parallel sequencing (454) libraries, we have identified three members of the ahSad gene family. Among them, only one gene, ahSad3, was exclusively expressed during seed development and in a manner fully corresponding to oil accumulation. Both ahSad3 homeologous genes (ahSad3A and ahSad3B) were recovered from the allotetraploid peanut, and their mRNA expression levels were characterized. The open reading frames for ahSad3A and ahSad3B are 98% identical and consist of 1,158 bp, encoding a 386-full-amino-acid protein, with one intron in the coding sequence. Comparisons of the sequences of these two homeologous genes revealed seven single-nucleotide polymorphisms and one triplet insertion in the coding region. Southern blot analysis indicated that there are only two copies of the ahSad3 gene in the peanut genome. Homeolog-specific gene expression analysis showed that both ahSad3 homeologs are expressed in developing seeds, but gene expression is significantly biased toward the B genome. Our results point to ahSad3 as a possible target gene for manipulation of fatty acid saturation in A. hypogaea.     

Reconsidering the relation between serum homocysteine and red blood cell distribution width: a cross-sectional study of a large cohort

Purpose: In a recent small sample study, red blood cell distribution width (RDW) was suggested as a predictor of homocysteine levels. The current study was aimed to reexamine this association in a large scale sample.

Methods: A retrospective cross-sectional study of healthy adults, conducted at Rabin Medical Center, during 2000–2014. Data were retrieved from the medical charts and a logistic regression controlling for interfering factors was carried out. Sensitivity analysis was implemented by exclusion of individuals with anaemia.

Results: Five thousand, five hundred fifty-four healthy individuals were included. Mean serum homocysteine level was 10.10 (SD 2.72) μmol/L. 34.4% of the study population had a homocysteine level higher than the upper limit of normal (10.8?μmol/L). Homocysteine showed no association with RDW (OR 1.00; 95% CI 0.97–1.03), but increased with age (OR 1.05; 95% CI 1.04–1.06) and decreased with a rise in haemoglobin (OR 0.77; 95% CI 0.71–0.83), and in the mean corpuscular volume (OR 0.86; 95% CI 0.85–0.88). Exclusion of individuals with anaemia did not reveal an association between homocysteine and RDW but found a somewhat smaller association between haemoglobin and RDW [OR 0.82; 95% CI 0.73–0.91].

Conclusions: In our large scale sample we did not find an association between RDW and serum homocysteine.     

The Tactile Communication between Cryptocentrus steinitzi (Pisces,Gobiidae) and Alpheus purpurilenticularis (Crustacea,Alpheidae)

The tactile alarm system between the symbiotic goby Cryptocentrus steinitzi and its burrowing shrimp partner Alpheus purpurilenticularis was investigated by underwater observations in the northern Red Sea. Warning signals by the goby which elicit the retreat of the shrimp into its burrow consist mainly of rapid tail flicks transmitted to the shrimp through its long antenna. No warning signals are given without that contact. The daily rhythm of the antennal contacts was described. Warning signals are emitted by the goby in a selective manner only in response to the approach of certain species of fish to the burrow entrance. The response of the shrimp to warning signals was described. The goby-shrimp communication system was used to study predator recognition in a series of controlled experiments. The sequence of the acts of the goby and shrimp was analyzed.     

Electrospray ionization tandem mass spectrometry (ESI-MS/MS) analysis of the lipid molecular species composition of yeast subcellular membranes reveals acyl chain-based sorting/remodeling of distinct molecular species en route to the plasma membrane.

Nano-electrospray ionization tandem mass spectrometry (nano-ESI-MS/MS) was employed to determine qualitative differences in the lipid molecular species composition of a comprehensive set of organellar membranes, isolated from a single culture of Saccharomyces cerevisiae cells. Remarkable differences in the acyl chain composition of biosynthetically related phospholipid classes were observed. Acyl chain saturation was lowest in phosphatidylcholine (15.4%) and phosphatidylethanolamine (PE; 16.2%), followed by phosphatidylserine (PS; 29.4%), and highest in phosphatidylinositol (53.1%). The lipid molecular species profiles of the various membranes were generally similar, with a deviation from a calculated average profile of approximately +/- 20%. Nevertheless, clear distinctions between the molecular species profiles of different membranes were observed, suggesting that lipid sorting mechanisms are operating at the level of individual molecular species to maintain the specific lipid composition of a given membrane. Most notably, the plasma membrane is enriched in saturated species of PS and PE. The nature of the sorting mechanism that determines the lipid composition of the plasma membrane was investigated further. The accumulation of monounsaturated species of PS at the expense of diunsaturated species in the plasma membrane of wild-type cells was reversed in elo3Delta mutant cells, which synthesize C24 fatty acid-substituted sphingolipids instead of the normal C26 fatty acid-substituted species. This observation suggests that acyl chain-based sorting and/or remodeling mechanisms are operating to maintain the specific lipid molecular species composition of the yeast plasma membrane.     

16S rRNA Phylogeny of Sponge-Associated Cyanobacteria

Phylogenetic analyses of 16S rRNA sequences of sponge-associated cyanobacteria showed them to be polyphyletic, implying that they derived from multiple independent symbiotic events. Most of the symbiont sequences were affiliated to a group of Synechococcus and Prochlorococcus species. However, other symbionts were related to different groups, such as the Oscillatoriales.     

Low and high affinity receptors mediate cellular uptake of heparanase

Heparanase is an endoglycosidase which cleaves heparan sulfate and hence participates in degradation and remodeling of the extracellular matrix. Importantly, heparanase activity correlated with the metastatic potential of tumor-derived cells, attributed to enhanced cell dissemination as a consequence of heparan sulfate cleavage and remodeling of the extracellular matrix barrier. Heparanase has been characterized as a glycoprotein, yet glycan biochemical analysis was not performed to date. Here, we applied the Qproteometrade mark GlycoArray kit to perform glycan analysis of heparanase, and compared the kit results with the more commonly used biochemical analyses. We employed fibroblasts isolated from patients with I-cell disease (mucolipidosis II), fibroblasts deficient of low density lipoprotein receptor-related protein and fibroblasts lacking mannose 6-phosphate receptor, to explore the role of mannose 6-phosphate in heparanase uptake. Iodinated heparanase has been utilized to calculate binding affinity. We provide evidence for hierarchy of binding to cellular receptors as a function of heparanase concentration. We report the existence of a high affinity, low abundant (i.e., low density lipoprotein receptor-related protein, mannose 6-phosphate receptor), as well as a low affinity, high abundant (i.e., heparan sulfate proteoglycan) receptors that mediate heparanase binding, and suggest that these receptors co-operate to establish high affinity binding sites for heparanase, thus maintaining extracellular retention of the enzyme tightly regulated.