Non-linear feedback processes and a latitudinal gradient in the climatic effects determine green spruce aphid outbreaks in the UK

The role of climatic fluctuations in determining the dynamics of insect populations has been a classical problem in population ecology. Here, we use long-term annual data on green spruce aphid populations at nine localities in the UK for determining the importance of endogenous processes, local weather and large-scale climatic factors. We rely on diagnostic and modelling tools from population dynamic theory to analyse these long-term data and to determine the role of the North Atlantic Oscillation (NAO) and local weather as exogenous factors influencing aphid dynamics. Our modelling suggests that the key elements determining population fluctuations in green spruce aphid populations in the UK are the strong non-linear feedback structure, the high potential for population growth and the effects of winter and spring weather. The results indicate that the main effect of the NAO on green spruce aphid populations is operating through the effect of winter temperatures on the maximum per capita growth rate (R_m). In particular, we can predict quite accurately the occurrence of an outbreak by using a simple logistic model with weather as a perturbation effect. However, model predictions using different climatic variables showed a clear geographical signature. The NAO and winter temperature were best for predicting observed dynamics toward the southern localities, while spring temperature was a much better predictor of aphid dynamics at northern localities. Although aphid species are characterized by complex life-cycles, we emphasize the value of simple and general population dynamic models in predicting their dynamics.     

Genetic approaches to reducing losses of stored grain to insects and diseases

Insects and diseases devour or damage a fifth or more of stored food grains each year in many parts of the world. Modern breeding and genomics promise progress in characterizing the resistance to the pests responsible for these losses that is present in the vast and diverse gene pool of cereals, as well as advances in incorporating this resistance into productive and acceptable crop varieties. The impact of such varieties could be dramatic in developing countries, where grain infestations are most common and harmful, and where surging populations require affordable food.     

Characterization of digestive gland esterase-lipase activity of juvenile redclaw crayfish Cherax quadricarinatus

Investigation of esterase-lipase activity in the digestive gland of redclaw crayfish Cherax quadricarinatus showed that the optimum enzyme activity occurred between 35 and 40 degrees C, with 100 mM NaCl at pH 8.5. Heavy metals completely inhibited and calcium ions partially inhibited enzyme activity. The enzyme activity diminished as the length of the fatty acid chain of substrates increased. Molecular masses for four isozymes were 43, 46, 63 and 118 kDa, respectively, as determined by PAGE.     

Red blood cell membrane defects

We present an overview of the currently known molecular basis of red cell membrane disorders. A detailed discussion of the structure of the red cell membrane and the pathophysiology and clinical aspects of its disorders is reported. Generally speaking, hereditary spherocytosis (HS) results from a loss of erythrocyte surface area. The mutations of most cases of HS are located in the following genes: ANK1, SPTB, SLC4A1, EPB42 and SPTA1, which encode for ankyrin, spectrin beta-chain, the anion exchanger 1 (band 3), protein 4.2 and spectrin alpha-chain, respectively. Hereditary elliptocytosis (HE) reflects a diminished elasticity of the skeleton. Its aggravated form, hereditary pyropoikilocytosis (HPP), implies that the skeleton undergoes further destabilization. The mutations responsible for HE and HPP, lie in the SPTA1 and SPTB gene, and in the EPB41 gene encoding protein 4.1. Allele alpha LELY is a common polymorphic allele, which plays the role of an aggravating factor when it occurs in trans of an elliptocytogenic allele of the SPTA1 gene. Southeast Asian ovalocytosis derives from a change in band 3. The genetic disorders of membrane permeability to monovalent cations required a positional cloning approach. In this respect, channelopathies represent a new frontier in the field. Dehydrated hereditary stomatocytosis (DHS) was shown to belong to a pleiotropic syndrome: DHS + fetal edema + pseudohyperkalemia, which maps 16q23-24. Splenectomy is strictly contraindicated in DHS and another disease of the same class, overhydrated hereditary stomatocytosis, because it increases the risk of thromboembolic accidents.     

Is there a benefit by the sequence anastrozole-formestane for postmenopausal metastatic breast cancer women?

To explore the different sequence interactions between reversible non-steroidal (anastrozole, ANZ and letrozole, LTZ) and non-reversible steroidal aromatase inhibitors (formestane, FOR and exemestane, EXE), we evaluated the clinical benefit (CB) in postmenopausal breast cancer patients, who had previously received anastrozole and subsequently formestane. In 19 out of 21 patients (90.5%), a clinical benefit response was achieved by anastrozole, with a median duration of 12 months. Out of the 21 women progressing on anastrozole, 12 achieved stable disease (SD)>/=6 months by formestane only. The overall clinical benefit was 66.5%. The median duration of clinical benefit was 11 months with a time to progression of 6.5 months. The median duration of clinical benefit in our series is similar to that reported in two phase II trials with the sequence aminogluthetimide-->formestane and aminogluthetimide-->exemestane as third-line hormonal therapy, suggesting a non-cross-resistance between the two classes of inhibitors.     

Chemokine-like receptor 1 expression and chemerin-directed chemotaxis distinguish plasmacytoid from myeloid dendritic cells in human blood

Plasmacytoid dendritic cells (pDCs) are versatile cells of the immune response, secreting type I IFNs and differentiating into potent immunogenic or tolerogenic APCs. pDCs can express adhesion and chemokine receptors for lymphoid tissues, but are also recruited by unknown mechanisms during tissue inflammation. We use a novel mAb specific for serpentine chemokine-like receptor 1 (CMKLR1) to evaluate its expression by circulating leukocytes in humans. We show that CMKLR1 is expressed by circulating pDCs in human blood, whereas myeloid DCs (mDCs) as well as lymphocytes, monocytes, neutrophils, and eosinophils are negative. We identify a major serum agonist activity for CMKLR1 as chemerin, a proteolytically activated attractant and the sole known ligand for CMKLR1, and we show that chemerin is activated during blood coagulation and attracts pDC but not mDC in ex vivo chemotaxis assays. We conclude that CMKLR1 expression and chemerin-mediated chemotaxis distinguish circulating pDCs from mDCs, providing a potential mechanism for their differential contribution to or regulation of immune responses at sites of bleeding or inflammatory protease activity.     

Hybrid origin of Japanese mice "Mus musculus molossinus": evidence from restriction analysis of mitochondrial DNA

The Japanese mouse, Mus musculus molossinus, has long been considered an independent subspecies of the house mouse. A survey of restriction- site haplotypes of mitochondrial DNA (mtDNA) showed that Japanese mice have two main maternal lineages. The most common haplotype is closely related to the mtDNA of the European subspecies M. m. musculus. The other common haplotype and two minor ones are closely related to each other and to the mtDNA of an Asiatic subspecies, M. m. castaneus. Two other rare variants are probably the result of recent contamination by European M. m. domesticus. The musculus type of mtDNA is found in the southern two-thirds of Japan, whereas the common castaneus type is found in the northern third and the minor variants are found sporadically throughout Japan. The castaneus mtDNA lineage had a few minor variants, whereas the musculus lineage was completely monomorphic. By contrast, the native population of M. m. castaneus and the Chinese and Korean musculus populations were highly polymorphic. These results suggest that M. m. molossinus is a hybrid between ancestral colonies, possibly very small, of M. m. musculus and M. m. castaneus, rather than an independent subspecies.      

Interferon effects on microfilament organization cellular fibronectin distribution, and cell motility in human fibroblasts

We have shown previously (Pfeffer et al., 1979, Exp. Cell Res. 121:111-120) that treatment of human fibroblasts, planted at a density of 2x10(3) cells/cm(2), with purified human fibroblasts interferon (640 U/ml) for 3 d at 37 degrees C decreases the overall rate of cell proliferation to 35-40 percent of the control value. In the present experiments we have characterized the phenotype of interferon-inhibited fibroblasts. The mean volume of trypsinized, interferon-treated cells was increased 31 percent abover that of control cells. The interferon-treated population was much more heterogeneous than the control population with respect to volume, and there was a considerable overlap in the volume distributions of the two populations. The cell surface area was, on the average, increased 65 percent after interferon treatment. More than 80 percent of the treated cells had enlarged nuclei, many of which were lobed, and the fraction of binucleated cells was increased fivefold. After interferon treatment, over 40 percent of the cells showed large actin-containing fibers in the form of multiple parallel arrays. Fewer than 5 percent of the control cells contained such large actin fibers. The number of actin fibers of all sizes was tripled in the treated fibroblasts on a per cell basis and, calculated per unit surface area of the cells, the number was increased 82 percent. In contrast, 10-nm filaments and microtubules did not appear to be increased in number per unit surface area of the cells. The increases per cell in the abundance of these structures were directly related to increased cell size. After interferon treatment, fibronection was distributed in arrays of long filaments covering most portions of the cell surface. Interferon treatment markedly decreased the rate of cell locomotion as well as membrane ruffling and saltatory movements of intracellular granules.