Conspecific thistle plant selection by a herbivorous ladybird beetle, Epilachna pustulosa

Host selection by Epilachna pustulosa Kôno (Coleoptera: Coccinellidae) was surveyed in an area of about 130 ares, focusing on the role of the spatial distribution pattern of the host plant, thistle Cirsium kamtschaticum Ledeb. (Asteraceae) and the environmental conditions of habitats where thistle plants were growing. A total of 198 thistle clones were found in the area studied, and approximately 40% showed some degree of E. pustulosa infestation by July. Eggs were only oviposited on thistle clones that were fed on by adults. Adult beetles and egg masses of E. pustulosa showed an aggregated distribution in the earlier season (June) among thistle clones. The distribution of adults became more random (but still aggregated) by the later season (July), along with an increase in the number of infested clones. Multiple logistic regression analyses revealed that clone size and soil moisture were consistently important for the beetle's choice of clones to feed on. The other logistic regression analyses indicated that thistle‐clone size and sunlight condition influenced egg distribution. Thistle clone selection by E. pustulosa changed with season from a rather strict selection in June to a more obscure one in July, expanding the range of thistle clones used as feeding and oviposition substrate.     

HJURP is involved in the expansion of centromeric chromatin

The CENP-A–specific chaperone HJURP mediates CENP-A deposition at centromeres. The N-terminal region of HJURP is responsible for binding to soluble CENP-A. However, it is unclear whether other regions of HJURP have additional functions for centromere formation and maintenance. In this study, we generated chicken DT40 knockout cell lines and gene replacement constructs for HJURP to assess the additional functions of HJURP in vivo. Our analysis revealed that the middle region of HJURP associates with the Mis18 complex protein M18BP1/KNL2 and that the HJURP-M18BP1 association is required for HJURP function. In addition, on the basis of the analysis of artificial centromeres induced by ectopic HJURP localization, we demonstrate that HJURP exhibits a centromere expansion activity that is separable from its CENP-A–binding activity. We also observed centromere expansion surrounding natural centromeres after HJURP overexpression. We propose that this centromere expansion activity reflects the functional properties of HJURP, which uses this activity to contribute to the plastic establishment of a centromeric chromatin structure.     

Oleanane-type triterpene oligoglycosides with pancreatic lipase inhibitory activity from the pericarps of Sapindus rarak

The methanolic extract from the pericarps of Sapindus rarak DC. was found to show pancreatic lipase inhibitory activity (IC₅₀ = ca. 614 μg/mL). From the extract, oleanane-type triterpene oligoglycosides, rarasaponins I–III (1–3), and raraoside A (4), were isolated together with 13 known saponins and four known sesquiterpene glycosides. Among them, several saponin constituents including rarasaponins I (1, IC₅₀ = 131 μM) and II (2, 172 μM), and raraoside A (4, 151 μM) inhibited pancreatic lipase activity, which were stronger than that of theasaponin E₁ (270 μM).     

Rapid corepressor exchange from the trp-repressor/operator complex: An NMR study of [ul-13C/15N]-l-tryptophan

Summary [ul-¹³C/¹⁵N]-l-tryptophan was prepared biosynthetically and its dynamic properties and intermolecular interaction with a complex of Escherichia coli trp-repressor and a 20 base-pair operator DNA were studied by heteronuclear isotope-edited NMR experiments. The resonances of the free and bound corepressor (l-Trp) were unambiguously identified from gradient-enhanced ¹⁵N–¹H HSQC, ¹³C–¹H HSQC, ¹³C-and ¹⁵N-edited 2D NOESY spectra. The exchange off-rate of the corepressor between the bound and free states was determined to be 3.4±0.52 s^–1 at 45°C, almost three orders of magnitude faster than the dissociation of the protein-DNA complex. Examination of the experimental NOE buildup curves indicates that it may be desirable to use longer mixing times than would normally be used for a large molecule, in order to detect weak intermolecular NOEs in the presence of exchange. Intermolecular NOEs from bound corepressor to trp-repressor and DNA were analyzed with respect to the mechanism of ligand exchange. This analysis suggests that, in order for the ligand to diffuse out of the complex, there must be significant movement or breathing of the protein and/or DNA.Abbreviations NOESY nuclear Overhauser enhancement spectroscopy - HSQC heteronuclear single-quantum coherence - PFG pulsed field gradient - l-Trp l-tryptophan     

Characterization of Streptomyces D3 derived from protoplast fusion between Streptomyces cyaneus 190-1 and Streptomyces griseoruber 42-9

Streptomyces D3, derived from protoplast fusion between Streptomyces cyaneus 190-1 and Streptomyces griseoruber 42-9, has the ability to produce high levels of xylose isomerase when grown on hemicellulosic materials such as xylan as the carbon source. Comparison between the partial nucleotide sequences of the 16S ribosomal RNA genes from S. cyaneus 190-1, S. griseoruber 42-9, and fusant D3 showed that the 16S rRNA gene of fusant D3 was identical to that of S. cyaneus 190-1. Partial sequence analysis of the xylose isomerase genes also indicated that the gene of fusant D3 was identical to that of S. cyaneus 190-1. The partial DNA fragments for the xylanase genes (xlnA and xlnB) of fusant D3 were amplified by PCR, and subjected to Southern hybridization analysis. The results revealed that the xlnB gene of fusant D3 was similar to that of S. cyaneus 190-1, but that the xlnA gene of fusant D3 was similar to that of S. griseoruber 42-9. These results suggest that the majority of the genome of fusant D3 may be derived from S. cyaneus 190-1.     

Role of Nine Repeating Sequences of the Mini-F Genome for Expression of F-Specific Incompatibility Phenotype and Copy Number Control

An autonomously replicating 2,248-base-pair DNA segment of the mini-F plasmid carries nine 19-base-pair repeating sequences. Five of the repeats are arranged in one direction and form the right cluster, whereas the remaining four repeats are arranged in the opposite direction and form the left cluster (Murotsu et al., Gene 15:257-271, 1981). Each cluster, cloned separately into the multicopy plasmid vector pBR322, exhibited a strong F-specific incompatibility phenotype (FIP). These clusters were thought to be responsible for the expression of IncB and IncC phenotypes, causing a switchoff function on mini-F replication. Mini-F DNA fragments containing two, three, or more than four repeats were inserted into pBR322. Cells carrying these recombinant plasmids exhibited, respectively, no, intermediate, and strong FIP intensity. Cloning of five repeats into pSC101, whose copy number is about 6 in contrast to 20 for pBR322, resulted in an FIP of intermediate intensity. Thus, the intensity of FIP reflects the dosage of repeats in a cell. The five repeats in the right cluster were eliminated from the mini-F derivative without impairing its autonomous-replicating ability (Bergquist et al., J. Bacteriol. 147:888-889, 1981; Kline and Palchavdhuri, Plasmid 4:281-289). Such deletion, however, caused a sixfold elevation of the copy number. When the eliminated cluster of repeats was reinserted in the derivative, the copy number was lowered to the original value, viz., 1 to 2. The position and orientation of this insertion was not important in the copy number control. Thus, the repeats are also related to copy number control. A model to account for the role of the repeating sequences in the control of copy number and FIP is discussed.     

Immunohistochemical study of granular cell tumors of the neurohypophysis

Six granular cell tumors (GCT) of the neurohypophysis were studied by immunohistochemical techniques. They were all labeled by peanut lectin (Arachis hypogaea) and three showed reactivity for S-100 protein. Unlike extracranial GCT, neuron specific enolase (NSE), myelin basic protein (MBP) and vimentin were not detected in the tumor cells. Glial fibrillary acidic protein (GFAP), keratin and desmin were also not observed. On the other hand, some showed reactivity for alpha-1 -antitrypsin (AAT), alpha-1-antichymotrypsin (AAC) and cathepsin B. These results suggest that neurohypophysial GCT have some features different from extracranial GCT and that they may not be derived from Schwann cells.     

Resistance of normal serum IgA and secretory IgA to bacterial IgA proteases: evidence for the presence of enzyme-neutralizing antibodies in both serum and secretory IgA, and also in serum IgG

Normal serum IgA and secretory IgA (sIgA) of subclass IgA1 were isolated from pooled human serum and milk, respectively. They were tested for their susceptibility to bacterial IgA proteases from Haemophilus influenzae, Streptococcus pneumoniae, Neisseria gonorrhoeae, and Neisseria meningitidis that cleave IgA of only the IgA1 subclass. They were also tested for susceptibility to a novel IgA-protease from Clostridium ramosum that cleaves IgA of the IgA1 as well as the IgA2 subclass of the A2m(1) allotype. Both normal serum IgA1 and sIgA1 exhibited resistance to most IgA proteases. The one exception was the IgA protease from C. ramosum which readily cleaved both the serum IgA1 and sIgA1 into Fab and Fc fragments. Secretory component (SC) had nothing to do with the resistance of these IgAs. The resistance of these IgAs to most of the IgA proteases was found to be due to their enzyme-neutralizing antibody activity, since the Fab but not the Fc fragment of sIgA1 showed enzyme-inhibitory activity against these IgA proteases. Similar enzyme-neutralizing antibody activity was found in the pepsin-digested normal serum IgG-(Fab')2 fragment. These results indicate that the induction of the enzyme-neutralizing antibodies against the bacterial IgA proteases took place not only in mucosal sIgA but also in serum IgA and IgG. No enzyme-neutralizing antibody activity against the novel IgA-protease of C. ramosum was detected in any immunoglobulin preparations used in the present study or in the serum of a patient who carries the IgA protease-producing strain of C. ramosum in his feces.