Burrowing behaviour in the crayfish, Cambarus diogenes diogenes girard

The crayfish, Cambarus diogenes diogenesGirard (1852), spends most of its life cycle in individually constructed underground burrows. The architectural behavioral patterns and sequences with which adult C. d. diogenes excavate an underground chamber were evaluated. Two motor patterns (Pushing and Carrying) and three burrow stages (shallow depression, angular pit, and burrow with two openings) were identified. During the development of burrowing behaviour in juveniles, a third motor pattern (Fanning) occurred. While the three motor patterns are functional soon after hatching, crayfish may learn to orient the Carrying motor pattern for the most efficient excavation of a stage-3 burrow with two openings. The ground-water level determined the final structure of a burrow.     

BCG-induced granulomatous pulmonary inflammation and splenomegaly in mice: A T-cell-dependent response

When C57BL/6 mice were injected iv with BCG in an oil-in-saline emulsion, they developed intense pulmonary granulomatous inflammation (PGI) and splenomegaly as well as chemotactic activity for macrophages and angiotensin-converting enzyme (ACE) in their lung fluids. PGI, splenomegaly, and levels of chemotactic activity and ACE were markedly reduced in T-cell-deficient “B” mice. The capacity to develop PGI was fully restored and splenomegaly was partially restored in “B” mice by the provision of syngeneic thymocytes, spleen cells, or purified T cells. These results indicate that the full expression of BCG-induced PGI is dependent upon thymus-derived cells and is associated with high levels of chemotactic activity for macrophages and ACE in the lung lavage fluid. Although BCG-induced splenomegaly appears to be T cell dependent, it did not reach its full magnitude in reconstituted “B” mice.     

Inhibition of the pancreatic microsome enzyme release phenomenon by inhibitors of signal peptidase activity

The protease-sensitive release of α-amylase from rat pancreatic microsomes, incubated at 37°C, was inhibited by protease inhibitors which have been reported to inhibit signal peptidase activity. Protease inhibitors which did not affect signal peptidase activity also failed to inhibit amylase release from microsomes. Although the observed amylase release was in the opposite direction to enzyme secretion and involved fully-synthesised proteins, rather than nascent peptides, it is proposed that the enzyme release phenomenon reported from this laboratory (Pearce et al. (1978) Biochem. J. 176, 611–614) is related to the protein transporting mechanism involved in secretion.     

The synthesis and cytotoxic activity of 1,3,4-tri-O-acetyl-2,6-dideoxy-L-arabino- and -L-lyxo-hexopyranose

Methyl 2,6-dideoxy-α-L-arabino-hexopyranoside (6) was prepared from L-rhamnose in five steps. Hydrolysis of6 with 50% aqueous acetic acid gave 2,6-dideoxy-L-arabino-hexopyranose. Treatment of 3,4-di-O-acetyl-L-rhamnal with acetic acid in the presence of acetic anhydride and 2% sulfuric acid afforded 1,2,3-tri-O-acetyl-2,6-dideoxy-L-arabino-hexopyranose in 65% yield. Selective benzoylation and subsequent mesylation of 6 afforded methyl 3-O-benzoyl-2,6-dideoxy-4-O-mesyl-α-L-arabino-hexopyranoside, which was treated with sodium benzoate and sodium azide in hexamethylphosphoric triamide to give the corresponding 3,4-dibenzoyl 9 and 4-azido 11 analogs. Hydrogenation and N-acetylation of 11 afforded the 4-acetamido derivative 12. Deprotection of 9 and 12 gave 2,6-dideoxy-L-lyxo-hexopyranose and 4-acetamido-2,4,6-trideoxy-L-lyxo-hexopyranose, which were characterized as their peracetates. The free and corresponding peracetylated derivatives were assayed for their ability to inhibit the growth of P388 leukemia cells in culture. Although the free sugars did not inhibit the replication of these tumor cells under the conditions employed, their peracetylated derivatives demonstrated significant activity.     

The Neisseria gonorrhoeae type IV pilus promotes resistance to hydrogen peroxide- and LL-37-mediated killing by modulating the availability of intracellular,labile iron

The Neisseria gonorrhoeae Type IV pilus is a multifunctional, dynamic fiber involved in host cell attachment, DNA transformation, and twitching motility. We previously reported that the N. gonorrhoeae pilus is also required for resistance against hydrogen peroxide-, antimicrobial peptide LL-37-, and non-oxidative, neutrophil-mediated killing. We tested whether the hydrogen peroxide, LL-37, and neutrophil hypersensitivity phenotypes in non-piliated N. gonorrhoeae could be due to elevated iron levels. Iron chelation in the growth medium rescued a nonpiliated pilE mutant from both hydrogen peroxide- and antimicrobial peptide LL-37-mediated killing, suggesting these phenotypes are related to iron availability. We used the antibiotic streptonigrin, which depends on free cytoplasmic iron and oxidation to kill bacteria, to determine whether piliation affected intracellular iron levels. Several non-piliated, loss-of-function mutants were more sensitive to streptonigrin killing than the piliated parental strain. Consistent with the idea that higher available iron levels in the under- and non-piliated strains were responsible for the higher streptonigrin sensitivity, iron limitation by desferal chelation restored resistance to streptonigrin in these strains and the addition of iron restored the sensitivity to streptonigrin killing. The antioxidants tiron and dimethylthiourea rescued the pilE mutant from streptonigrin-mediated killing, suggesting that the elevated labile iron pool in non-piliated bacteria leads to streptonigrin-dependent reactive oxygen species production. These antioxidants did not affect LL-37-mediated killing. We confirmed that the pilE mutant is not more sensitive to other antibiotics showing that the streptonigrin phenotypes are not due to general bacterial envelope disruption. The total iron content of the cell was unaltered by piliation when measured using ICP-MS suggesting that only the labile iron pool is affected by piliation. These results support the hypothesis that piliation state affects N. gonorrhoeae iron homeostasis and influences sensitivity to various host-derived antimicrobial agents.     

<Emphasis Type="Italic">Narcissus tazetta</Emphasis> lectin shows strong inhibitory effects against respiratory syncytial virus,influenza A (H1N1, H3N2, H5N1) and B viruses

A mannose-binding lectin (Narcissus tazetta lectin [NTL]) with potent antiviral activity was isolated and purified from the bulbs of the Chinese daffodil Narcissus tazetta var. chinensis, using ion exchange chromatography on diethylaminoethyl (DEAE)-cellulose, affinity chromatography on mannose-agarose and fast protein liquid chromatography (FPLC)-gel filtration on Superose 12. The purified lectin was shown to have an apparent molecular mass of 26 kDa by gel filtration and 13 kDa by SDS-PAGE, indicating that it is probably a dimer with two identical subunits. The cDNA-derived amino acid sequence of NTL as determined by molecular cloning also reveals that NTL protein contains a mature polypeptide consisting of 105 amino acids and a C-terminal peptide extension. Three-dimensional modelling study demonstrated that the NTL primary polypeptide contains three subdomains, each with a conserved mannose-binding site. It shows a high homology of about 60%–80% similarity with the existing monocot mannose-binding lectins. NTL could significantly inhibit plaque formation by the human respiratory syncytial virus (RSV) with an IC₅₀ of 2.30 μg/ml and exhibit strong antiviral properties against influenza A (H1N1, H3N2, H5N1) and influenza B viruses with IC₅₀ values ranging from 0.20 μg/ml to 1.33 μg/ml in a dose-dependent manner. It is worth noting that the modes of antiviral action of NTL against RSV and influenza A virus are significantly different. NTL is effective in the inhibition of RSV during the whole viral infection cycle, but the antiviral activity of NTL is mainly expressed at the early stage of the viral cycle of influenza A (H1N1) virus. NTL with a high selective index (SI=CC₅₀/IC₅₀≥141) resulting from its potent antiviral activity and low cytotoxicity demonstrates a potential for biotechnological development as an antiviral agent.     

Human histone gene organization : Identification of a histone gene polymorphism prevalent in a black population

Analysis of the restriction enzyme digests of total genomic DNAs from a broad spectrum of human cell lines and from individuals with different genetic backgrounds, by hybridization with a series of cloned human histone sequences, indicated restriction site polymorphisms (RSPs) for two adjacent human histone genes which reside on chromosome 1. In most cell lines and individuals examined we observed a single 2.05 kb H4 histone HindIII fragment and a 7.0 kb H3 histone HindIII fragment. In contrast, the polymorphisms were manifested as a 2.15 kb H4 HindIII fragment and a 9.1 kb H3 HindIII fragment. From population studies, we were able to show that there is no linkage disequilibrium between these two polymorphic restriction sites. Nor was there any apparent correlation between the presence of the H3/H4 histone polymorphisms and maintenance of the transformed karyotype, passage in culture, transformation or tumor progression. These chromosome 1 H3 and H4 histone gene polymorphisms are common in the American Black population and, in our survey of individuals, were not found in the American Caucasian population. Among the American Blacks studied, the frequency of the H3 HindIII(-) allele is 43% and of the H4 HindIII(-) allele 30%. In limited family studies, we were unable to detect recombination between these two physically linked alleles.