Relative frequencies of polymorphisms of variation in Block 2 repeats and 5' recombinant types of Plasmodium falciparum msp1 alleles

The mechanisms producing the genetic polymorphism at Plasmodium falciparum merozoite surface antigen-1 locus (pfmsp1) include the insertion and deletion of the different type of dimorphic Block 2 9-nucleotide repeat units as well as the intragenic recombination. To study relative occurrence frequencies of these two distinct mechanisms, we have developed a sensitive PCR strategy to identify both 5' recombinant types and the number of Block 2 repeats from the same sample. This method can specifically detect the target 5' recombinant type (Blocks 2-6) at the sensitivity of 1-4 copies of the pfmsp1. Applying the new method to field isolates from the Solomon Islands enabled us to identify six different 5' recombinant types and variation in Block 2 repeat number in three of them, thus distinguishing 10 different alleles. Distribution of these alleles in local three villages in the study area suggests that frequencies of variation in the number of Block 2 9-bp repeats and recombination events within Blocks 2-6 are mutually independent and the frequency of repeat variation is relatively high as compared to that of recombination events at the pfmsp1 locus in P. falciparum populations from the Solomon Islands.     

Apollon ubiquitinates SMAC and caspase-9, and has an essential cytoprotection function

Apollon (also known as BRUCE or BIRC6) is a large protein containing baculoviral-IAP-repeat (BIR) and ubiquitin-conjugating enzyme (UBC) domains at the amino- and carboxy termini, respectively. Apollon inhibits apoptosis, but its molecular and physiological function remains unclear. Here we report that Apollon binds to, ubiquitinates and facilitates proteasomal degradation of SMAC and caspase-9, which both contain IAP-binding motifs. Targeted disruption of Apollon in mice caused embryonic and neonatal lethality. Notably, SMAC induced apoptosis in Apollon-deficient cells, but not in Apollon-expressing cells. Furthermore, the IAP-binding motif of SMAC was required to induce apoptosis in Apollon-deficient cells. These results suggest that Apollon has an essential function in preventing SMAC-induced apoptosis.     

Cellular stiffness response to external deformation: tensional homeostasis in a single fibroblast

Stiffness responses of fibroblasts were measured by scanning probe microscopy, following elongation or compression by deformation of an elastic substrate by 8%. The cellular stiffness, reflecting intracellular tension acting along stress fibers, decreased or increased instantly in response to the elongating or compressing stimuli, respectively. After this rapid change, the fibroblasts gradually recovered to their initial stiffness during the following 2 h, and then stabilized. The cells did not show conspicuous changes in shape after the 8% deformation during the SPM measurements. Fluorescence examination for GFP-actin demonstrated that the structure of the stress fibers was not altered noticeably by this small degree of deformation. Treatment with Y-27632, to inhibit myosin phosphorylation and abrogate cellular contractility, eliminated the change in stiffness after the mechanical elongation. These results indicate that fibroblasts possess a mechanism that regulates intracellular tension along stress fibers to maintain the cellular stiffness in a constant equilibrium state.     

Structure-activity relationships for alpha-glucosidase inhibition of baicalein, 5,6,7-trihydroxyflavone: the effect of A-ring substitution

In order to estimate the effects of the A-ring hydroxyl group of baicalein (5,6,7-trihydroxyflavone, 1) on rat intestinal alpha-glucosidase inhibition, flavone, monohydroxyflavones, dihydroxyflavones, and methylated derivatives of 5,6,7-trihydroxyflavone were used for the structure-activity relationship (SAR) study. The importance of the 6-hydroxyl group of baicalein was validated for an exertion of the activity. And also, the tested flavones which lacked a hydroxyl substituent on any of positions 5, 6, or 7, showed no activity. Hence, the 5,6,7-trihydroxyflavone structure was concluded to be crucial for the potent inhibitory activity. In addition, an introduction of electron-withdrawing or electron-donating groups at position 8 of baicalein led to a dramatic decrease for activity, except for 8-fluoro-5,6,7-trihydroxyflavone, which carried a less bulky substituent on position 8. Hence, this result suggested that a sterically bulky substituent on C-8 of baicalein was detrimental for the activity regardless of its electronic nature. Through examining the inhibitory mechanism of baicalein against rat intestinal alpha-glucosidase, it was suggested to be a mixed type inhibition.     

A novel method for producing a foodstuff from defatted black sesame seed that inhibits allergen absorption

A method is proposed to produce a foodstuff that inhibits allergen absorption through the intestinal tract. Defatted black sesame (Sesamum indicum) seeds as a starting material were hydrolyzed with a crude preparation of trypsin at 40 degrees C and pH 8 for 3 hrs while gently stirring to generate an active peptide. The resulting hydrolysate was heated to inactivate the trypsin and make the active components soluble. An extract was obtained by centrifugation and then freeze-dried. Ser-Asn-Ala-Leu-Val-Ser-Pro-Asp-Trp-Ser-Met-Thr-Gly-His (compound 1) as an active peptide, and sesamino1 2'-O-beta-glucopyranosyl-(1-->2)-O-[beta-glucopyranosyl(1-->6)]-O-beta-glucopyranoside (compound 2) and sesamino1 2'-O-beta-glucopyranosyl (1-->2)-O-beta-glucopyranoside (compound 3) were identified as active lignan glycosides in an in vitro model by using Caco-2 cells. Compound 1 was active at 10(-7) M and compounds 2 and 3 at 10(-5) M.     

Rapid protein anchoring into the membranes of Mammalian cells using oleyl chain and poly(ethylene glycol) derivatives

The cell membrane is an important interface for communication with extracellular events, and incorporation of bioactive substances, such as antibodies and receptors, into the cell membrane may enhance the potential abilities of cells. Gene manipulation, chemical modification of membrane proteins, and cell surface painting using a GPI anchor have been performed to introduce substances into cell membranes. Furthermore, many lipid anchors have also been used to modify lipid membranes such as liposomes. In this study, we have focused on developing an easy and rapid method for anchoring of substances including macromolecular proteins into the membranes of living mammalian cells. We employed a single oleyl chain derivative coupled with hydrophilic poly(ethylene glycol) (PEG90, the ethyleneoxide (EO) unit is 90) to facilitate solubilization in water. This water-soluble derivative was designated Biocompatible Anchor for Membrane (BAM). Some proteins (streptavidin, EGFP and an antibody) were coupled with BAM90 at the distal terminal of PEG and rapidly (within a few minutes) anchored into the membranes of various cells (NIH3T3, 32D, Ba/F3, hybridoma 9E10). However, the anchored BAM90 disappeared from the cell membranes within 4-5 h in serum-free culture media, and moreover, the retention time of anchoring was shortened (1-2 h) in culture medium containing 10% FBS. We further prepared a dioleylphosphatidylethanolamine (DOPE)-PEG derivative (DOPE-BAM80, the EO unit is 80) as a double oleyl chain derivative for comparison with the single oleyl chain derivative, BAM90. The retention time of anchored DOPE-BAM80 was longer than that of BAM90 and more than 8 h in culture media with and without 10% serum. Furthermore, the treatment time of DOPE-BAM80 for anchoring was nearly as short (within a few minutes) as that of BAM90. In addition, both types of BAMs, BAM90 and DOPE-BAM80, showed no cytotoxicity. Therefore, DOPE-BAM80 is useful for protein anchoring to cells. Although the utilization of BAM90 is considered to be limited, it is expected to useful in restricted environments, for example, in tissues such as the cornea, peritoneum, bladder, and various mucosae, which are less exposed to serum. Thus, we suggest the possibility that both types of BAM can be applied to cell surface engineering.     

Inhibitory effects of ellagi- and gallotannins on rat intestinal alpha-glucosidase complexes

The clove ellagitannins and their related polygalloyl-glucoses inhibited maltase activity of rat intestinal alpha-glucosidases. The structure-activity relationship study of those galloylglucoses, varying the extent of galloylation on the glucose core, with the ellagitannins, indicated that an increasing number of galloyl units in the molecule lead to an increase in the inhibitory activity. Penta-O-galloyl-beta-D-glucose, with five galloyl groups showed the highest inhibitory activity. On the other hand, hexahydroxydiphenoyl units contained in the ellagitannins had little effect on the activity. After separation of maltase-glucoamylase and sucrase-isomaltase complexes from the crude mixture of the rat alpha-glucosidases, the inhibitory activities of the galloylglucose derivatives against each complex were examined. The inhibitory influence on the maltase-glucoamylase complex was more potent than on the sucrase-isomaltase complex.     

Cloning and nucleotide sequence of the mycodextranase gene from Streptomyces sp. J-13-3

Mycodextranase (EC 3.2.1.61) is an alpha-glucanase that cleaves alpha-1,4-bonds of alternating alpha-1,3- and alpha-1,4-linked D-glucan (nigeran). The gene encoding mycodextranase from Streptomyces sp. J-13-3 was cloned by hybridization with a degenerate oligonucleotide probe from the amino-terminal amino acid sequence of the enzyme and its nucleotide structure was analyzed. The open reading frame consisted of 1,803 base pairs encoding a signal peptide of 60 amino acids and a mature protein of 540 amino acids with a calculated molecular weight of 56,078. The deduced amino acid sequence showed weak similality to a chitinase homolog from Streptomyces lividans and a chitinase from Xanthomonas sp.