Immune-related proteins induced in the hemolymph after aseptic and septic injury differ in honey bee worker larvae and adults

We have employed the proteomic approach in combination with mass spectrometry to study the immune response of honey bee workers at different developmental stages. Analysis of the hemolymph proteins of noninfected, mock-infected and immune-challenged individuals by polyacrylamide gel electrophoresis showed differences in the protein profiles. We present evidence that in vitro reared honey bee larvae respond with a prominent humoral reaction to aseptic and septic injury as documented by the transient synthesis of the three antimicrobial peptides (AMPs) hymenoptaecin, defensin1, and abaecin. In contrast, young adult worker bees react with a broader spectrum of immune reactions that include the activation of prophenoloxidase and humoral immune responses. At least seven proteins appeared consistently in the hemolymph of immune-challenged bees, three of which are identical to the AMPs induced also in larvae. The other four, i.e., phenoloxidase (PO), peptidoglycan recognition protein-S2, carboxylesterase (CE), and an Apis-specific protein not assigned to any function (HP30), are induced specifically in adult bees and, with the exception of PO, are not expressed after aseptic injury. Structural features of CE and HP30, such as classical leucine zipper motifs, together with their strong simultaneous induction upon challenge with bacteria suggest an important role of the two novel bee-specific immune proteins in response to microbial infections.     

Soil-to-plant and soil-to-grain transfer of 137Cs in field-grown maize hybrids during two contrasting seasons: assessing the phenotypic variability and its genetic component

Field-grown maize hybrids were assessed for variability in ¹³⁷Cs accumulation in vegetative parts of young and mature maize shoots and grains during 2 years with contrasting climatic conditions. Trials were carried out at different sites in the Tula region of Russia, which is characterized by a highly homogenous soil classified as Luvic Chernozem according to FAO/UNESCO, and average contamination levels of about 509–564 Bq ¹³⁷Cs kg⁻¹ soil. In the first year, 19 hybrids were tested. The two hybrids with the highest and the two with the lowest ¹³⁷Cs concentration ratios (C _r) were also tested in the second year, together with another 11 hybrids. All samples were additionally assessed for their potassium content. In both investigation periods ¹³⁷Cs accumulation in vegetative shoots and grains was found to vary up to more than twofold between hybrids. However, C _r values of those hybrids that showed a relatively low ¹³⁷Cs accumulation in the first year were not necessarily low in the second year, and the ratio between the ¹³⁷Cs C _r of low- and high-accumulating hybrids was much smaller than in the year before. In both vegetative shoots and grains the variance caused by the different years was larger than the genotypic variance, thus indicating the limits of genotype selection for this trait. Significant correlations were determined between the ⁴⁰K and ¹³⁷Cs C _r values in the same tissue, but for one hybrid indications for uncoupling of the two traits were found. Average Cs/K ratios in young shoots, mature shoots and grains were 0.06, 0.05 and 0.02, respectively, indicating tissue- and stage-specific regulation of accumulation within each plant. The findings are discussed with respect to new approaches towards a better understanding of ¹³⁷Cs accumulation and its potential reduction in plants. Katharina Schneider was deceased.     

The Simian Immunodeficiency Virus Δnef Vaccine, after Application to the Tonsils of Rhesus Macaques, Replicates Primarily within CD4+ T Cells and Elicits a Local Perforin-Positive CD8+ T-Cell Response

Deletion of the nef gene from simian immunodeficiency virus (SIV) strain SIVmac239 yields a virus that undergoes attenuated growth in rhesus macaques and offers substantial protection against a subsequent challenge with some SIV wild-type viruses. We used a recently described model to identify sites in which the SIVDeltanef vaccine strain replicates and elicits immunity in vivo. A high dose of SIVDeltanef was applied to the palatine and lingual tonsils, where it replicated vigorously in this portal of entry at 7 days. Within 2 weeks, the virus had spread and was replicating actively in axillary lymph nodes, primarily in extrafollicular T-cell-rich regions but also in germinal centers. At this time, large numbers of perforin-positive cells, both CD8(+) T cells and CD3-negative presumptive natural killer cells, were found in the tonsil and axillary lymph nodes. The number of infected cells and perforin-positive cells then fell. When autopsy studies were carried out at 26 weeks, only 1 to 3 cells hybridized for viral RNA per section of lymphoid tissue. Nevertheless, infected cells were detected chronically in most lymphoid organs, where the titers of infectious virus could exceed by a log or more the titers in blood. Immunocytochemical labeling at the early active stages of infection showed that cells expressing SIVDeltanef RNA were CD4(+) T lymphocytes. A majority of infected cells were not in the active cell cycle, since 60 to 70% of the RNA-positive cells in tissue sections lacked the Ki-67 cell cycle antigen, and both Ki-67-positive and -negative cells had similar grain counts for viral RNA. Macrophages and dendritic cells, identified with a panel of monoclonal antibodies to these cells, were rarely infected. We conclude that the attenuated growth and protection observed with the SIVDeltanef vaccine strain does not require that the virus shift its characteristic site of replication, the CD4(+) T lymphocyte. In fact, this immunodeficiency virus can replicate actively in CD4(+) T cells prior to being contained by the host, at least in part by a strong killer cell response that is generated acutely in the infected lymph nodes.     

Glucose-stat, a glucose-controlled continuous culture.

A predictive and feedback proportional control algorithm, developed for fed-batch fermentations and described in a companion paper (G. L. Kleman, J. J. Chalmers, G. W. Luli, and W. R. Strohl, Appl. Environ. Microbiol. 57:910-917, 1991), was used in this work to control a continuous culture on the basis of the soluble-glucose concentration (called the glucose-stat). This glucose-controlled continuous-culture system was found to reach and maintain steady state for 11 to 24 residence times when four different background glucose concentrations (0.27, 0.50, 0.7, and 1.5 g/liter) were used. The predictive-plus-feedback control system yielded very tight control of the continuous nutristat cultures; glucose concentrations were maintained at the set points with less than 0.003 standard error. Acetate production by Escherichia coli B in glucose-stats was found not to be correlated with the level of steady-state soluble-glucose concentration.     

Endogenous formation of the prostaglandin endoperoxine metabolite,thromboxane B2, by brain tissue

Thromboxane B₂ was formed from endogenous precursors during short incubations of guinea pig and rat cerebral cortex. The amount formed by guinea pig brain tissue was 5–6 times the formation of prostaglandin F_2α and E₂. Noradrenalin stimulated and indomethacin and mercaptoethanol inhibited thromboxane B₂ formation. The mass spectrum of the brain compound was identical to thromboxane B₂ formed from arachidonic acid by guinea pig lung and human platelets.     

Genomic instability and cancer: networks involved in response to DNA damage

A new approach to cancer and new methods in examining rare human chromosome breakage syndromes have brought to light complex interactions between different pathways involved in damage response, cell cycle checkpoint control and DNA repair. The genes affected in these different syndromes are involved in networks of processes that respond to DNA damage and prevent chromosomal aberrations during the cell cycle. The genes involved include the ATM, ATR, FA-associated genes, NBS1 and the cancer susceptibility genes BRCA1 and BRCA2. Chromosomal instability is a common feature of many human cancers and most of the instability syndromes, characterized by sensitivity to different types of DNA damage, also show increased cancer susceptibility. Better understanding of these syndromes and their links with familial cancer provide new insight into associations between defects in DNA damage response, cell cycle control, DNA repair and cancer. Understanding the damage response repair networks that these studies are revealing will have important implications for the development of cancer management and treatment.     

Receptor-selective mutants of apoptosis-inducing ligand 2/tumor necrosis factor-related apoptosis-inducing ligand reveal a greater contribution of death receptor (DR) 5 than DR4 to apoptosis signaling

Apoptosis-inducing ligand 2 (Apo2L), also called tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), triggers programmed cell death in various types of cancer cells but not in most normal cells. Apo2L/TRAIL is a homotrimeric protein that interacts with five receptors: death receptor 4 (DR4) and DR5 mediate apoptosis activation, whereas decoy receptor 1 (DcR1), DcR2, and osteoprotegerin counteract this function. Many cancer cell lines express both DR4 and DR5, and each of these receptors can initiate apoptosis independently of the other. However, the relative contribution of DR4 and DR5 to ligand-induced apoptosis is unknown. To investigate this question, we generated death receptor-selective Apo2L/TRAIL variants using a novel approach that enables phage display of mutated trimeric proteins. Selective binding to DR4 or DR5 was achieved with three to six-ligand amino acid substitutions. The DR4-selective Apo2L/TRAIL variants examined in this study showed a markedly reduced ability to trigger apoptosis, whereas the DR5-selective variants had minimally decreased or slightly increased apoptosis-inducing activity. These results suggest that DR5 may contribute more than DR4 to Apo2L/TRAIL-induced apoptosis in cancer cells that express both death receptors.     

Antibacterial activities in various tissues of the horse mussel, Modiolus modiolus

A search for antibacterial activity in different organs/tissues of the horse mussel, Modiolus modiolus, was conducted. Dried samples were extracted with 60% (v/v) acetonitrile, containing 0.1% (v/v) trifluoroacetic acid. Due to high salt content, two liquid phases were obtained; an acetonitrile-rich phase (ACN extract) and an aqueous phase. The aqueous phase was further subjected to solid phase extraction (SPE). Eluates from SPE and ACN extracts were tested for antibacterial, lysozyme, and toxic activity. Antibacterial activity was demonstrated in extracts from several tissues, including plasma, haemocytes, labial palps, byssus, mantle, and gills. Some of the extracts were sensitive to proteinase K treatment, indicating antibacterial peptides and/or proteins. Lysozyme-like activity and toxic activity against Artemia salina nauplii was detected in fractions from the gills, mantle, muscle, and haemocytes. Results from this study indicate that M. modiolus is a promising source for identifying novel drug lead compounds.     

The cell surface of Lactobacillus reuteri ATCC 55730 highlighted by identification of 126 extracellular proteins from the genome sequence

Bioinformatical analyses of a draft genome sequence of the commensal bacterium Lactobacillus reuteri ATCC 55730 revealed 126 genes encoding putative extracellular proteins. The function, localization and distribution in bacterial species were predicted. Interestingly, few proteins possessed LPXTG motifs or C-terminal transmembrane anchors. Instead eight proteins were putatively anchored by GW repeats and several secreted proteins were likely to be re-associated to the surface. The majority of the extracellular proteins were widely distributed, i.e., found universally or in gram-positive bacteria, but 24 were only detected in L. reuteri. Further, the number of transporters was lower, while the number of enzyme was higher than in related species.