Isolation of Two Plasticizers,Bis(2-ethylhexyl) Terephthalate and Bis(2-ethylhexyl) Phthalate,from Capparis spinosa L. Leaves

Many plants have been known to be contaminated and accumulate plasticizers from the environment, including water sources, soil, and atmosphere. Plasticizers are used to confer elasticity and flexibility to various fiber and plastic products. Consumption of plasticizers can lead to many adverse effects on human health, including reproductive and developmental toxicity, endocrine disruption, and cancer. Herein, we report for the first time that two plasticizers, bis(2-ethylhexyl) terephthalate (DEHT) and bis(2-ethylhexyl) phthalate (DEHP), have been isolated from the leaves of Capparis spinosa L. (the caper bush), a plant that is widely used in food seasonings and traditional medicine. 297 mg/kg of DEHT and 48 mg/kg of DEHP were isolated from dried and grounded C. spinosa L. leaves using column chromatography and semi-preparative high-performance liquid chromatography. Our study adds to the increase in the detection of plasticizers in our food and medicinal plants and to the alarming concern about their potential adverse effects on human health.     

Mechanism of metal ion biosorption by fungal biomass

Alkali extracted mycelial biomass from Aspergillus niger, referred to as Biosorb, was found to sequester metal ions (Cd²⁺, Cu²⁺, Zn²⁺, Ni²⁺ and Co²⁺) efficiently both from dilute and concentrated solutions upto 10% of its weight (w/w). Sequestration of metal ions from a mixture was also efficient but with attendant antagonisms. The kinetics of metal binding by Biosorb indicated that it is a rapid process and about 70–80% of the metal is removed from solution in 5 min followed by a slower rate. The mechanism of metal binding is shown to be due to exchange of calcium and magnesium ions of the Biosorb during which equimolar concentrations of both the ions were released into the medium. Following this an efficient procedure for the regeneration and reuse of Biosorb was standardized by washing the biosorbent with calcium and magnesium solution (0.1 m). Biosorbents prepared from Neurospora, Fusarium and Penicillium also exhibited similar mechanisms for metal ion binding, though they had a lower metal binding capacity when compared with Biosorb. Chemical modification of carboxylic acid functional groups of the Biosorb resulted in loss of 90% of metal binding capacity which could not be restored even on regeneration. The significance of this finding on the metal sequestration mechanisms of microbial biosorbents is discussed.     

Phytoplankton primary production in a mesotrophic pond in sub-tropical Bangladesh

Annual gross primary productivity in mesotrophic Shahidullah Hall pond (Dhaka, Bangladesh) was 1383.35 g C m⁻² y⁻¹ (arithmetic mean). Daily primary productivity (between 1.6 and 6.8 g C m⁻² d⁻¹ was correlated with chlorophylla, day length and dissolved silica. Chlorophylla related significantly withk, incident light, SRP, alkalinity and conductivity. A negative correlation existed between biomass and rainfall. Productivity, biomass, conductivity, alkalinity, and SRP increased after mid-winter.k, I _k andZ _eu varied according seasonally.P _max related directly with temperature. Seasonal variation of ∝ ^B was 0.0049–0.0258 mg C (mg chla mmol PAR)⁻¹ m⁻². Q₁₀ was 2.12, community respiration 1334.99 g C m⁻² y⁻¹, and the underwater light climate 186.43μE m⁻² s⁻¹.     

PilC of pathogenic Neisseria is associated with the bacterial cell surface

Adherence of pathogenic Neisseria to target host cells is mediated by pili. PilC1 and PilC2 are two high-molecular-weight proteins involved in pilus assembly and cellular adherence functions of the pili. Inactivation of pilC1 or pilC2 in N. meningitidis resulted in clones that expressed the same number of pili as the parent, contained no alterations in pilE and showed no detectable differences in PilE glycosylation. However, the PilC2+ pilC1- mutant showed much reduced adherence to target cells, indicating that production of PilC1 is essential for pilus-mediated adherence. To study further the functional differences between the meningococcal pilC genes, we determined the complete nucleotide sequence of pilC1 and pilC2 of N. meningitidis. Alignment of six PilC sequences demonstrated that PilC is composed of both conserved and variable regions. By immunogold labelling of bacterial sections we showed that PilC is present in the membranes of both piliated and non-piliated bacteria. Further, we demonstrated that PilC is associated with the bacterial cell surface.     

The PiGMaP consortium linkage map of the pig (Sus scrofa)

A linkage map of the porcine genome has been developed by segregation analysis of 239 genetic markers. Eighty-one of these markers correspond to known genes. Linkage groups have been assigned to all 18 autosomes plus the X Chromosome (Chr). As 69 of the markers on the linkage map have also been mapped physically (by others), there is significant integration of linkage and physical map data. Six informative markers failed to show linkage to these maps. As in other species, the genetic map of the heterogametic sex (male) was significantly shorter (16.5 Morgans) than the genetic map of the homogametic sex (female) (21.5 Morgans). The sex-averaged genetic map of the pig was estimated to be 18 Morgans in length. Mapping information for 61 Type I loci (genes) enhances the contribution of the pig gene map to comparative gene mapping. Because the linkage map incorporates both highly polymorphic Type II loci, predominantly microsatellites, and Type I loci, it will be useful both for large experiments to map quantitative trait loci and for the subsequent isolation of trait genes following a comparative and candidate gene approach.     

Isoelectric focusing--polynucleotide/polyacrylamide-gel electrophoresis. A technique to separate and characterize nuclease activities.

Individual native nuclease activities from human leucocytes are separated by using two-dimensional gel electrophoresis in an apparatus that allows the simultaneous running of 28 gels. Proteins are separated by isoelectric focusing in a disc gel, followed by electrophoresis into a slab gel containing DNA. Protein denaturants are avoided in the second dimension by the use of a running pH well above the optimal pH for DNAase (deoxyribonuclease) activity. Electrophoresed gels are incubated in appropriate buffers to activate nuclease activity. After staining for intact DNA, the positions of active enzymes, unobscured by the presence of other proteins, are revealed as colourless spots in a reddish-purple field. The technique is easy to use and is sensitive to 50pg of DNAase I. Versatility is provided by the use of either acidic or basic electrophoresis running buffers and by the use of specific gel incubation conditions to reveal different sets of enzyme activities. Two DNAases active at pH 7.4 in the presence of Mg2+ and Ca2+, and sixteen DNAases active at acidic pH and not requiring metals, are detected. Treatment of the human enzymes with specific glycosidases reveals that many of the human DNAases are glycoproteins containing negatively charged moieties and may be derived from modification of parent activities.     

Differential uptake of liposomes varying in size and lipid composition by parenchymal and kupffer cells of mouse liver

Using liposomes differing in size and lipid composition, we have studied the uptake characteristics of the liver parenchymal and Kupffer cells. Desferal labeled with iron-59 was chosen as a radiomarker for the liposomal content, because Desferal in its free form does not cross cellular membranes. At various time intervals after an intravenous injection of liposomes into mice, the liver was perfused with collagenase, and the cells were separated in a Percoll gradient. It was found that large multilamellar liposomes (diameter of about 0.5 μm) were mainly taken up by the Kupffer cells. For these large liposomes, the rate of uptake by Kupffer cells was rapid, with maximum uptake at around 2 hours after liposome injection. Unexpectedly, small unilamellar liposomes (diameter of about 0.08 μm) were less effectively taken up by Kupffer cells, and the rate of uptake was slow, with a maximum uptake at about 10 hours after liposome injection. In contrast, parenchymal cells were more effective in taking up small liposomes and the uptake of large liposomes was negligible. In addition, liposomes made with a galactolipid as part of the lipid constituents appeared to have higher affinity to parenchymal cells than liposomes made without the galactolipid. These findings should be of importance in designing suitable liposomes for drug targeting.     

Evidence of synergy between Thy-1 and CD3/TCR complex in signal delivery to murine thymocytes for cell death.

The potential role of Thy-1 in CD3/TCR complex-mediated signal delivery to murine thymocytes was studied. Ag-mimicking cross-linked anti-CD3 mAb stimulated suspension of thymocytes from adult (6 to 8 wk old) mice for a brisk free cytoplasmic calcium ion ([Ca2+]i) rise, low level of inositol phosphate production, and marginal increase in tyrosine-specific phosphorylation of 110/120-kDa and 40-kDa cellular proteins. Weak but sustained [Ca2+]i rise, low inositol phosphate production, and weak protein tyrosine phosphorylation were also induced by the cross-linked anti-Thy-1 mAb that mimicked the putative natural ligand. The signal delivered via either of these two pathways was however insufficient for definitively promoting cell death and DNA fragmentation in the adult thymocytes. Here we demonstrated that anti-Thy-1 mAb synergized with anti-CD3 mAb for inducing a long-lasting prominent [Ca2+]i rise, definite inositol 1,4,5-triphosphate and inositol 1,3,4,5-tetrakiphosphate production, and extensive tyrosine-specific phosphorylation of 110/120-, 92-, 75-, and 40-kDa proteins, which resulted in marked promotion of cell death and DNA fragmentation in the adult thymocytes. This unique anti-Thy-1 antibody activity was confirmed to be directed to glycosylphosphatidylinositol-anchored Thy-1, and was distinguished from the known anti-L3T4 activity that augmented the CD3-mediated signal transduction in a different manner. The synergistic actions of anti-CD3 and anti-Thy-1 mAb obligatorily required the cross-linking of the two mAb together. The anti-CD3 and anti-Thy-1 mAb cross-linked together acted on immature thymocytes from newborn (less than 24 h after birth) mice for rather more extensive promotion of protein tyrosine phosphorylation and cell death. In addition, they affected peripheral T lymphocytes for accelerating protein tyrosine phosphorylation but not cell death. These results suggest a novel function of glycosylphosphatidylinositol-anchored Thy-1 as a possible unique intrathymic intensifier of the CD3/TCR complex-delivered signal for negative thymocyte selection.