Giardia in beaver (Castor canadensis) and nutria (Myocastor coypus) from east Texas

We examined the prevalence of Giardia sp. infection in nuisance beaver (Castor canadensis) and nutria (Myocastor coypus) in east Texas. From October 1992 through September 1993, 100 beaver and 30 nutria were collected in routine wildlife management activities conducted by the U.S. Department of Agriculture-Animal and Plant Health Inspection Service-Texas Animal Damage Control Service. Fecal and duodenal mucoid samples were preserved from each animal. Fecal samples were examined for the occurrence of Giardia sp. cysts using the Merifluor immunoassay detection kit: 30 beaver (30.0%) and 20 nutria (66.7%) were positive for Giardia sp. Duodenal mucoid samples were examined for Giardia sp. trophozoites using trichrome staining. with 26 beaver (26.0%) and 20 nutria (73.3%) testing positive. Combining both techniques resulted in 33 beaver (33.0%) and 22 nutria (73.3%) testing positive for Giardia sp. We found no relationship between Giardia sp. and host age, sex, river system, habitat, county, or season in beaver. However, a relationship was found when season and habitat were considered together. No relationship was found between Giardia sp. and age, river system, habitat, county, or season in nutria: however, more males (87.5%) were infected than females (46.4%).     

Tau blocks traffic of organelles, neurofilaments, and APP vesicles in neurons and enhances oxidative stress

We studied the effect of microtubule-associated tau protein on trafficking of vesicles and organelles in primary cortical neurons, retinal ganglion cells, and neuroblastoma cells. Tau inhibits kinesin-dependent transport of peroxisomes, neurofilaments, and Golgi-derived vesicles into neurites. Loss of peroxisomes makes cells vulnerable to oxidative stress and leads to degeneration. In particular, tau inhibits transport of amyloid precursor protein (APP) into axons and dendrites, causing its accumulation in the cell body. APP tagged with yellow fluorescent protein and transfected by adenovirus associates with vesicles moving rapidly forward in the axon (approximately 80%) and slowly back (approximately 20%). Both movements are strongly inhibited by cotransfection with fluorescently tagged tau (cyan fluorescent protein-tau) as seen by two-color confocal microscopy. The data suggests a linkage between tau and APP trafficking, which may be significant in Alzheimer's disease.     

Metabolic mapping with bioluminescence: basic and clinical relevance

This review is focused on metabolic mapping in biological tissue with quantitative bioluminescence and single photon imaging. Metabolites, such as ATP, glucose and lactate, can be imaged quantitatively and within microscopic dimensions in cryosections from shock frozen biological specimens using enzyme reactions and light emission by luciferases. The technique has been applied in numerous targets and models of experimental biomedical research, such as multicellular spheroids, various organs of laboratory animals in a physiological or pathophysiological state, and even in plant seeds. Among numerous other aspects, data obtained with this method have contributed to the elucidation of mechanisms that are involved in the development of necrosis in multicellular spheroids. The combination of the bioluminescence technique with immunohistochemistry, autoradiography or in situ hybridization can considerably reduce ambiguities in the interpretation of the experimental results. Although, an invasive technique, bioluminescence imaging has been used most intensively in clinical oncology using tumor biopsies taken at the first diagnosis of the disease. It has been shown for squamous cell carcinomas of the head and neck and of the uterine cervix that accumulation of high levels of lactate in the primary lesions is associated with a high risk of metastasis formation and a reduced overall and disease-free patient survival. Thus, metabolic imaging can provide additional information on the degree of malignancy and the prognosis of tumors which may help the oncologist in improving specific treatment approaches for each individual malignant disease. Last but not least, metabolic mapping in clinical oncology has stimulated a number of investigations in basic cancer research on mechanisms that underlie the correlation between tumor metabolism and malignancy.     

Relative importance of predators and parasitoids for cereal aphid control

Field experiments with manipulations of natural enemies of plant-feeding insects may show how a diverse enemy group ensures an important ecosystem function such as naturally occurring biological pest control. We studied cereal aphid populations in winter wheat under experimentally reduced densities of: (i) ground-dwelling generalist predators (mostly spiders, carabid and staphylinid beetles); (ii) flying predators (coccinellid beetles, syrphid flies, gall midges, etc.) and parasitoids (aphidiid wasps), and a combination of (i) and (ii), compared with open controls. Aphid populations were 18% higher at reduced densities of ground-dwelling predators, 70% higher when flying predators and parasitoids were removed, and 172% higher on the removal of both enemy groups. Parasitoid wasps probably had the strongest effect, as flying predators occurred only in negligible densities. The great importance of parasitism is a new finding for aphid control in cereal fields. In conclusion, a more detailed knowledge of the mechanisms of natural pest control would help to develop environmentally sound crop management with reduced pesticide applications.     

Efficient intracellular delivery of a protein and a low molecular weight substance via recombinant polyomavirus-like particles

Efficient encapsulation of foreign molecules like proteins and low molecular weight drugs into polyoma virus-like particles (capsoids) was achieved by the development of an anchoring technique based upon the specific interaction of the inner core protein VP2 with VP1 pentamers. A stretch of 49 amino acids of VP2 served as an anchor molecule, either expressed as a fusion protein with green fluorescent protein (GFP) or covalently linked to methotrexate (MTX). The loaded capsoids showed regular morphology and stability for several months. GFP and MTX were internalized into cells in vitro, as was demonstrated by the detection of GFP and VP1 fluorescence in mouse fibroblasts and the cytostatic effect of intracellularly released MTX on leukemia T cells.     

Mitochondrial inner membrane permeabilisation enables mtDNA release during apoptosis

During apoptosis, pro‐apoptotic BAX and BAK are activated, causing mitochondrial outer membrane permeabilisation (MOMP), caspase activation and cell death. However, even in the absence of caspase activity, cells usually die following MOMP. Such caspase‐independent cell death is accompanied by inflammation that requires mitochondrial DNA (mtDNA) activation of cGAS‐STING signalling. Because the mitochondrial inner membrane is thought to remain intact during apoptosis, we sought to address how matrix mtDNA could activate the cytosolic cGAS‐STING signalling pathway. Using super‐resolution imaging, we show that mtDNA is efficiently released from mitochondria following MOMP. In a temporal manner, we find that following MOMP, BAX/BAK‐mediated mitochondrial outer membrane pores gradually widen. This allows extrusion of the mitochondrial inner membrane into the cytosol whereupon it permeablises allowing mtDNA release. Our data demonstrate that mitochondrial inner membrane permeabilisation (MIMP) can occur during cell death following BAX/BAK‐dependent MOMP. Importantly, by enabling the cytosolic release of mtDNA, inner membrane permeabilisation underpins the immunogenic effects of caspase‐independent cell death.     

Compositional factors influencing cell surface hydrophobicity ofPasteurella multocida variants

The influence of macromolecules other than lipopolysaccharide on the hydrophobic properties ofPasteurella multocida was investigated by assessing cell surface hydrophobicity (CSH) after experimentally modifying surfaces of various strains. CSH of hydrophobic variants was enhanced by growth on blood-supplemented medium and mechanical shearing, whereas chloramphenicol, oxytetracycline, trypsin, and pronase E treatments decreased CSH. No such modifications were observed for hydrophilic strains. Microscopic observations revealed hydrophilic strains to be heavily encapsulated in contrast to hydrophobic strains. Repeated subculturing reduced encapsulation with a concomitant increase in CSH for one hydrophilic strain while exerting no changes in the other hydrophilic strain examined. Hyaluronidase removal of capsular material from a serotype A strain resulted in increased CSH; subsequent exposure to pronase E resulted in partial restoration of hydrophilicity. These data suggest the encapsulation of hydrophilicP. multocida strains masks a relatively hydrophobic surface that is conferred, at least in part, by the presence of one or more surface-exposed proteins common to both hydrophilic and hydrophobic variants.     

The frequency of wing damage in a migrating butterfly

The ability to fly is crucial for migratory insects. Consequently, the accumulation of damage on the wings over time can affect survival, especially for species that travel long distances. We examined the frequency of irreversible wing damage in the migratory butterfly Vanessa cardui to explore the effect of wing structure on wing damage frequency, as well as the mechanisms that might mitigate wing damage. An exceptionally high migration rate driven by high precipitation levels in their larval habitats in the winter of 2018–2019 provided us with an excellent opportunity to collect data on the frequency of naturally occurring wing damage associated with long-distance flights. Digital images of 135 individuals of V. cardui were collected and analyzed in Germany. The results show that the hindwings experienced a greater frequency of damage than the forewings. Moreover, forewings experienced more severe damage on the lateral margin, whereas hindwings experienced more damage on the trailing margin. The frequency of wing margin damage was higher in the painted lady butterfly than in the migrating monarch butterfly and in the butterfly Pontia occidentalis following artificially induced wing collisions. The results of this study could be used in future comparative studies of patterns of wing damage in butterflies and other insects. Additional studies are needed to clarify whether the strategies for coping with wing damage differ between migratory and nonmigratory species.     

Inheritance of Resistance to Pratylenchus penetrans in Alfalfa

Fifty-two alfalfa (Medicago sativa L.) clones, randomly selected from the cultivar Baker and the experimental line MNGRN-4, were evaluated for resistance (based on nematode reproduction) to Pratylenchus penetrans in growth chamber tests (25 C). Twenty-five clones, representing the range of nematodes and eggs per plant, were selected and retested. Four moderately resistant and two susceptible alfalfa clones were identified. Inheritance of resistance to P. penetrans was studied in these six clones using a diallel mating design. The S₁, Fl, and reciprocal progenies differed for numbers of nematodes and eggs per g dry root and for shoot and root weights (P < 0.05). Resistance, measured as numbers of nematodes in roots, was correlated between parental clones and their S₁ families (r = 0.94), parental clones and their half-sib families (r = 0.81), and S₁ and half-sib families (r = 0.88). General combining ability (GCA) effects were significant for nematode resistance traits. Both GCA and specific combining ability (SCA) effects were significant for plant size traits, but SCA was more important than GCA in predicting progeny plant size. Reciprocal effects were significant for both nematode resistance and plant size traits, which may slow selection progress in long-term selection programs. However, the GCA effects are large enough that breeding procedures that capitalize on additive effects should be effective in developing alfalfa cultivars with resistance to P. penetrans.