The potential impacts of the arrival of the harlequin ladybird, Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae), in Britain

Abstract.  1. The harlequin ladybird, Harmonia axyridis , has recently arrived in Britain.
2. This species has been introduced from Asia into many parts of the world for biological control purposes.
3. In many parts of North America it has become the predominant aphidophagous coccinellid in less than 20 years, and in north-western Europe it is spreading and increasing in number rapidly.
4. Since establishment in North America and continental Europe, reports of its effectiveness as a biological control agent of aphids and coccids have been accompanied by accounts of negative effects on other aphidophagous species and humans.
5. Here the potential impacts of the arrival of the harlequin ladybird in Britain are assessed.     

Asymmetric distribution of metals in the Xenopus laevis oocyte: a synchrotron X-ray fluorescence microprobe study.

The asymmetric distribution of many components of the Xenopus oocyte, including RNA, proteins, and pigment, provides a framework for cellular specialization during development. During maturation, Xenopus oocytes also acquire metals needed for development, but apart from zinc, little is known about their distribution. Synchrotron X-ray fluorescence microprobe was used to map iron, copper, and zinc and the metalloid selenium in a whole oocyte. Iron, zinc, and copper were asymmetrically distributed in the cytoplasm, while selenium and copper were more abundant in the nucleus. A zone of high copper and zinc was seen in the animal pole cytoplasm. Iron was also concentrated in the animal pole but did not colocalize with zinc, copper, or pigment accumulations. This asymmetry of metal deposition may be important for normal development. Synchrotron X-ray fluorescence microprobe will be a useful tool to examine how metals accumulate and redistribute during fertilization and embryonic development.     

DNA repair in higher plants

Numerous studies have demonstrated a requirement in plants for repair of DNA damage arising from either intrinsic or extrinsic sources. Investigations also have revealed a capacity for repair types of DNA damage, and conversely, identified mutants apparently defective in such repair. This article provides a concise overview of nuclear DNA repair mechanisms in higher plants, particularly those processes concerned with the repair of UV-induced lesions, and includes surveys of UV-sensitive mutants and genes implicated in DNA repair.     

Polyamine deficiency alters EGF receptor distribution and signaling effectiveness in IEC-6 cells

Cell growth andmigration are essential processes for the differentiation, maintenance,and repair of the intestinal epithelium. Epidermal growth factor (EGF)is an important factor in the reorganization of the cytoskeletonrequired for both processes. Because we had previously foundsignificant changes in the cytoskeleton during polyamine deficiency, itwas of interest to know whether those changes could prevent EGF fromstimulating growth and migration. Polyamine biosynthesis in IEC-6 cellswas interrupted by treatment with -difluoromethylornithine (DFMO), aspecific inhibitor of ornithine decarboxylase, the primaryrate-limiting enzyme of polyamine biosynthesis. DFMO halted cellproliferation and inhibited cell migration, and neither function couldbe normally stimulated by EGF. Immunocytochemistry of the transferrinreceptor (used as a marker for the endocytic pathway) revealed anabnormal distribution of the EGF receptor (EGFR) 10 min after bindingEGF. Polyamine deficiency depleted the cells of interiormicrofilaments, thickened the actin cortex, and prevented the promptassociation of EGF-bound EGFR with actin. EGF-stimulated 170-kDaprotein tyrosine phosphorylation and the kinase activity of purifiedmembrane EGFR were reduced by 50%. Immunoprecipatated EGFR proteinconcentration, however, was not reduced by polyamine deficiency. All ofthese changes could be prevented by supplementation with putrescine.Cytoskeletal disruption, reduced EGFR phosphorylation and kinaseactivity, aberrant intracellular EGFR distribution, and delayedassociation with actin filaments suggest a partial explanation for thedependence of epithelial cell growth and migration on polyamines.

     

Callus formation and differentiation in tissue cultures of normal and cytoplasmic male sterile sorghum,pepper, sunflower,and tobacco

Summary The primary goal of this study was to establish callus cultures of selected plant taxa containing both normal (N) and cytoplasmic male-sterile (CMS) lines. A secondary goal was to attempt to differentiate the calli into whole flowering plants. Undifferentiated and organ differentiated calli were produced in specific lines of N and CMS sorghum, pepper, sunflower, and tobacco. Calli from both N and CMS lines of a given species developed similarly and grew well. Even though whole flowering plants have not yet been produced from any of the lines, this approach allows for good production of callus for studies dealing with CMS. Journal Paper No. J-7741 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa. Project No. 1914.     

A Method for the Preparation of Undecalcified Bone Sections for Light Microscopy and Microradiography

A method which gives good quality 1-2 μm thick sections of undecaldfied cancellous and thin cortical bones for light miuoscopy is described. Formalin fixed material is dehydrated in graded acetones and embedded in a modiEed formula of Spurr's low viscosity embedding medium. After a 16 hour polymerisation period at 60 C, sections are cut at 1-2 μm thickness on a Porter-Blum JB4A rotary microtome Using glass knives. Sections are attached to clean glass slides with heat, the resin degraded in bromine vapour and removed in acetone. This allows comparative ease of staining. The technique is rapid, does not interfere with tetracycline fluorescence and the same specimens can be used to prepare thick sections for microradiography.     

Distribution of Streptococcal Groups in Clinical Specimens with Evaluation of Bacitracin Screening

During a 2-year period, 4,968 strains of beta-hemolytic streptococci were examined for the clinical source distribution and bacitracin sensitivity of each group. In the upper respiratory tract, groups A (51.7%) and C (20.4%) accounted for most of the isolates, and in wounds and exudates group A (79.1%) made up most of the isolates. Group B (71.2%) was the major component of isolates from the genitorinary tract and, while composing 29.3% of the lower respiratory tract isolates, competed with group A (18.8%) and the nongroupables (22.8%) for supremacy. Bacitracin screening showed that 0.5% of group A streptococci were resistant, and sensitive non-group A isolates were group B (2.6%), group C (6.0%), group G (8.0%), and the nongroupables (2.2%). It was found that those groups which were most predominant in wounds and the upper respiratory tract gave the highest rate of false positives with bacitracin, whereas the predominant group of the genitourinary tract gave the lowest rate of false positives.     

The excretion and degradation of chondroitin 4-sulphate administered to guinea pigs as free chondroitin sulphate and as proteoglycan

The excretion and degradation was studied of (35)S-labelled 4-chondroitin sulphate injected into guinea pigs in the form of proteoglycan isolated from cartilage and in the form of free chondroitin 4-sulphate prepared from the same proteoglycan by proteolysis. When the proteoglycan was injected there was a delay of about 15-20min before significant amounts or radioactivity were excreted, whereas after injection of chondroitin 4-sulphate a considerable amount of radioactivity was excreted within 10min and a much higher proportion of the radioactive dose was excreted in 1h or 24h compared with the proteoglycan. In both cases, however, a major part of the radioactivity was not excreted even in 24h. Sterile conditions were used to collect the radioactive material directly from the bladder. When chondroitin 4-sulphate was injected, the molecular sizes of injected and excreted materials were similar, as assessed by gel chromatography on Sephadex G-200, whereas when proteoglycan was injected the molecular size of the excreted labelled material was similar to that of the chondroitin 4-sulphate chains in the original proteoglycan. In neither case did the size of the excreted labelled material change with time over 1h, and low-molecular-weight labelled material was virtually absent. In contrast, when urine was collected for 24h without preservative the labelled material in it was extensively degraded after either the proteoglycan or chondroitin 4-sulphate had been given. Chondroitin 4-sulphate became similarly degraded when incubated with non-sterile urine, but not when the urine was passed through a bacterial filter, suggesting that degradation was caused by contaminating micro-organisms in the experiments in which urine was collected for 24 h. It is concluded that chondroitin 4-sulphate chains of about 18000 molecular weight can be excreted readily as such, whereas intact proteoglycans must be degraded to free glycosaminoglycans first, although both are taken up by the tissues more rapidly than they are excreted.     

Lipid intermediates in the biosynthesis of the wall teichoic acid in Staphylococcus lactis I3

1. Particulate enzyme systems have been prepared from Staphylococcus lactis I3 which effect the synthesis of wall teichoic acid (a polymer containing a repeating unit in which d-glycerol 1-phosphate is attached to the 4-position on N-acetylglucosamine 1-phosphate) from the nucleotide precursors CDP-glycerol and UDP-N-acetylglucosamine. By using nucleotides labelled with (32)P and (14)C it has been shown that the synthesis proceeds via lipid intermediates. 2. Two intermediates have been found. In one of these N-acetylglucosamine 1-phosphate is present, whereas in the other the repeating unit of the teichoic acid occurs. 3. The simultaneous formation of the teichoic acid, a poly-(N-acetylglucosamine 1-phosphate) and an unidentified lipid, together with the poor ability of most particulate systems to synthesize polymer and the instability of the lipid intermediates themselves, have interfered with pulse-labelling experiments. Nevertheless, the biosynthetic sequence has been elucidated. It is concluded that the intermediates are derivatives of undecaprenol phosphate.