Factors affecting capture of Cryptolestes ferrugineus (Coleoptera: Laemophloeidae) in traps placed in stored wheat

Cryptolestes ferrugineus (Stephens), the rusty grain beetle, infests grain externally and is a common pest of stored wheat throughout the world. Detection and population estimation of this insect are important in avoiding discounts at the point of sale. Laboratory experiments compared number of insect captures in the WNB II probe and PC trap in stored grain with a known insect density. Capture rates were strongly related to insect densities in wheat. In a simultaneous test of insect density, ranging from one to three insects per kilogram, and temperatures between 20 and 40 degrees C, insect captures in WB II probe traps increased linearly with insect density in the grain but had a quadratic response to temperature. Hole density, ranging from 40 to 120 holes along a 15-cm stretch of the trap body, was unrelated to number of insect captures. Probe trap diameters ranging from 26 to 60 mm were also unrelated to insect captures. Finally, dead rusty grain beetles were recovered in probe traps. The recovery of dead insects increased with insect density when insects were found in an aggregated dispersal pattern, such as would be found following phosphine fumigation of grain. Experiments discussed here will help grain managers understand how probe traps may be used in C. ferrugineus population estimation.     

Regulation of alpha-1B adrenergic receptor localization, trafficking, function, and stability

The alpha-1 adrenergic receptors (alpha(1)ARs) play important roles in normal physiology and in many disease states, and understanding their signaling pathways and regulatory mechanisms is thus of considerable relevance, in particular for identifying pharmacological targets for therapeutic modulation. The expression, function, localization, trafficking, and stability of these receptors are all subject to complex regulation by diverse molecular mechanisms. This article highlights recent studies from our laboratory and others focused on the localization and trafficking of the alpha-1B adrenergic receptor (alpha(1B)AR) subtype and on changes in its stability that are likely to be involved in regulating receptor expression. The role(s) of protein kinase C in alpha(1B)AR sequestration, endocytosis, and extracellular signal-regulated kinase (ERK) activation are summarized, and evidence for alpha(1B)AR localization in caveolae/rafts is presented. Receptor structural domains involved in the multiple steps and mechanisms of agonist-induced desensitization are described. Finally, aspects of alpha(1B)AR structural stability that appear to control its drug-induced up- and down-regulation are discussed. Our understanding of regulation for the alpha(1B)AR subtype provides a model for studies of the differential regulation of the other alpha(1)AR subtypes and may lead to identification of new molecular targets for therapeutic intervention in a variety of disease states.     

Defective phagocytosis and clearance of Pseudomonas aeruginosa in the lung following bone marrow transplantation

Bone marrow transplantation (BMT) is an important therapeutic option for a variety of malignant and nonmalignant disorders. Unfortunately, BMT recipients are at increased risk of infection, and in particular, pulmonary complications occur frequently. Although the risk of infection is greatest during the neutropenic period immediately following transplant, patients are still vulnerable to pulmonary infections even after neutrophil engraftment. We evaluated the risk of infection in this postengraftment period by using a well-established mouse BMT model. Seven days after syngeneic BMT, B6D2F(1) mice are no longer neutropenic, and by 3 wk, they demonstrate complete reconstitution of the peripheral blood. However, these mice remain more susceptible throughout 8 wk to infection after intratracheal administration of Pseudomonas aeruginosa; increased mortality in the P. aeruginosa-infected BMT mice correlates with increased bacterial burden in the lungs as well as increased systemic dissemination. This heightened susceptibility to infection was not secondary to a defect in inflammatory cell recruitment to the lung. The inability to clear P. aeruginosa in the lung correlated with reduced phagocytosis of the bacteria by alveolar macrophages (AMs), but not neutrophils, decreased production of TNF-alpha by AMs, and decreased levels of TNF-alpha and IFN-gamma in the bronchoalveolar lavage fluid following infection. Expression of the beta(2) integrins CD11a and CD11c was reduced on AMs from BMT mice compared with wild-type mice. Thus, despite restoration of peripheral blood count, phagocytic defects in the AMs of BMT mice persist and may contribute to the increased risk of infection seen in the postengraftment period.     

Role of diminished epithelial GM-CSF in the pathogenesis of bleomycin-induced pulmonary fibrosis

Evidence derived from human and animal studies strongly supports the notion that dysfunctional alveolar epithelial cells (AECs) play a central role in determining the progression of inflammatory injury to pulmonary fibrosis. We formed the hypothesis that impaired production of the regulatory cytokine granulocyte-macrophage colony-stimulating factor (GM-CSF) by injured AECs plays a role in the development of pulmonary fibrosis. To test this hypothesis, we used the well-characterized model of bleomycin-induced pulmonary fibrosis in rats. GM-CSF mRNA is expressed at a constant high level in the lungs of untreated or saline-challenged animals. In contrast, there is a consistent reduction in expression of GM-CSF mRNA in the lung during the first week after bleomycin injury. Bleomycin-treated rats given neutralizing rabbit anti-rat GM-CSF IgG develop increased fibrosis. Type II AECs isolated from rats after bleomycin injury demonstrate diminished expression of GM-CSF mRNA immediately after isolation and in response to stimulation in vitro with endotoxin compared with that in normal type II cells. These data demonstrate a defect in the ability of type II epithelial cells from bleomycin-treated rats to express GM-CSF mRNA and a protective role for GM-CSF in the pathogenesis of bleomycin-induced pulmonary fibrosis.     

Location Isn’t Everything: Timing of Spawning Aggregations Optimizes Larval Replenishment

Many species of reef fishes form large spawning aggregations that are highly predictable in space and time. Prior research has suggested that aggregating fish derive fitness benefits not just from mating at high density but, also, from oceanographic features of the spatial locations where aggregations occur. Using a probabilistic biophysical model of larval dispersal coupled to a fine resolution hydrodynamic model of the Florida Straits, we develop a stochastic landscape of larval fitness. Tracking virtual larvae from release to settlement and incorporating changes in larval behavior through ontogeny, we found that larval success was sensitive to the timing of spawning. Indeed, propagules released during the observed spawning period had higher larval success rates than those released outside the observed spawning period. In contrast, larval success rates were relatively insensitive to the spatial position of the release site. In addition, minimum (rather than mean) larval survival was maximized during the observed spawning period, indicating a reproductive strategy that minimizes the probability of recruitment failure. Given this landscape of larval fitness, we take an inverse optimization approach to define a biological objective function that reflects a tradeoff between the mean and variance of larval success in a temporally variable environment. Using this objective function, we suggest that the length of the spawning period can provide insight into the tradeoff between reproductive risk and reward.     

Evaluation of spatial and temporal patterns of insect damage and aflatoxin level in the pre‐harvest corn fields to improve management tactics

Spatial and temporal patterns of insect damage in relation to aflatoxin contamination in a corn field with plants of uniform genetic background are not well understood. After previous examination of spatial patterns of insect damage and aflatoxin in pre‐harvest corn fields, we further examined both spatial and temporal patterns of cob‐ and kernel‐feeding insect damage, and aflatoxin level with two samplings at pre‐harvest in 2008 and 2009. The feeding damage by each of the ear/kernel‐feeding insects (i.e., corn earworm/fall armyworm damage on the silk/cob, and discoloration of corn kernels by stink bugs) and maize weevil population were assessed at each grid point with five ears. Sampling data showed a field edge effect in both insect damage and aflatoxin contamination in both years. Maize weevils tended toward an aggregated distribution more frequently than either corn earworm or stink bug damage in both years. The frequency of detecting aggregated distribution for aflatoxin level was less than any of the insect damage assessments. Stink bug damage and maize weevil number were more closely associated with aflatoxin level than was corn earworm damage. In addition, the indices of spatial–temporal association (χ) demonstrated that the number of maize weevils was associated between the first (4 weeks pre‐harvest) and second (1 week pre‐harvest) samplings in both years on all fields. In contrast, corn earworm damage between the first and second samplings from the field on the Belflower Farm, and aflatoxin level and corn earworm damage from the field on the Lang Farm were dissociated in 2009.     

Myelin Deficits Produced by Early Postnatal Exposure to Inorganic Lead or Triethyltin Are Persistent

Abstract: Long-Evans rat pups were exposed to either inorganic lead (400 mg Pb as lead acetate/kg body weight/day) or triethyltin sulfate (1.0 mg/kg body weight/day), by gastric intubation, from 2 days through 29 days of age. The rats were then weaned and placed on standard lab chow ad libitum. At 30 days of age, leadtreated rats exhibited statistically significant decreases in body and brain weights (22% and 17%, respectively), and the concentration of forebrain myelin was significantly reduced, by 21% relative to the 4.9 mg myelin protein/g brain in control rats. Although these animals recovered from the body weight deficits after several months, the deficits in brain weight and myelin concentration were still present at 120 days of age. This suggests that the lead-induced myelin deficits were permanent. Lead levels in brain, which were maximal at 30 days of age when the treatment was terminated, decreased more slowly than in other organs and were still 30% of maximal levels at 120 days of age. Triethyltin-treated animals also had significantly decreased body and brain weights (20% and 11%, respectively) at 30 days of age, and an even more severe reduction in forebrain myelin concentration (33%). These animals also regained a normal body weight by 120 days of age, but again the deficits in brain weight and myelin concentration persisted. Tin levels in brain and other organs had decreased to control levels by 60 days of age. Animals malnourished by maternal deprivation to match the body weights of the treated animals had myelin deficits that were less severe than those in the treated animals at 30 days of age (approximately 11% less than controls); however, these myelin deficits also persisted throughout the subsequent 90-day recovery period examined. The apparent lack of recovery from CNS myelin deficits produced by neonatal exposure to different heavy metals or to malnutrition reemphasizes the vulnerability of the developing nervous system to a wide range of metabolic insults.