Action of carbendazim on the development of Nosema bombycis Naegeli in silkworm Bombyx mori L.

Abstract:  Carbendazim, a benzimidazole compound is effective in curing pebrine disease in silkworm, Bombyx mori , caused by Nosema bombycis , if treatment is given within 48 h post-infection or before the parasite establishes itself in the host tissue. Ultrastructural evidence of the action of carbendazim showed an adverse effect of the drug on both merogonic and sporogonic stages of the parasite in the midgut and silk gland of the silkworm. The drug caused elongation, vacuolation and depletion of cytoplasmic contents of the meront, sporont, sporoblast and spore stages of N. bombycis .     

Neuromechanical control of upper airway patency during sleep.

Obstructive sleep apnea is caused by pharyngeal occlusion due to alterations in upper airway mechanical properties and/or disturbances in neuromuscular control. The objective of the study was to determine the relative contribution of mechanical loads and dynamic neuromuscular responses to pharyngeal collapse during sleep. Sixteen obstructive sleep apnea patients and sixteen normal subjects were matched on age, sex, and body mass index. Pharyngeal collapsibility, defined by the critical pressure, was measured during sleep. The critical pressure was partitioned between its passive mechanical properties (passive critical pressure) and active dynamic responses to upper airway obstruction (active critical pressure). Compared with normal subjects, sleep apnea patients demonstrated elevated mechanical loads as demonstrated by higher passive critical pressures [-0.05 (SD 2.4) vs. -4.5 cmH2O (SD 3.0), P = 0.0003]. Dynamic responses were depressed in sleep apnea patients, as suggested by failure to lower their active critical pressures [-1.6 (SD 3.5) vs. -11.1 cmH2O (SD 5.3), P < 0.0001] in response to upper airway obstruction. Moreover, elevated mechanical loads placed some normal individuals at risk for sleep apnea. In this subset, dynamic responses to upper airway obstruction compensated for mechanical loads and maintained airway patency by lowering the active critical pressure. The present study suggests that increased mechanical loads and blunted neuromuscular responses are both required for the development of obstructive sleep apnea.     

Mode of Action of the Toxin from Pseudomonas phaseolicola: I. Toxin Specificity, Chlorosis, and Ornithine Accumulation

The specificity of the Pseudomonas phaseolicola toxin for enzyme inhibition and its relationship to toxin-induced chlorosis in bean leaves (Phaseolus vulgaris L.) was examined. The toxin showed no significant inhibitory activity against glutamine synthetase, glutamine transferase, carbamyl phosphate synthetase, aspartate carbamoyltransferase, or arginase at concentrations 100-fold higher than that needed to inhibit ornithine carbamoyltransferase by 50%.     

Inhibition of ethylene evolution in papaya pulp tissue by benzyl isothiocyanate

Papaya (Carica papaya L.) pulp tissue disks in an incubation medium composed of 0.4 m sucrose evolve ethylene at an optimum pH of 5.25 at 30 C. Disks of young preclimacteric fruit evolve the gas linearly with fruit age until fruit age reaches 4 months. Disks from 5-month-old postclimacteric fruit produce approximately 5-fold more ethylene than disks from 4-month-old fruit. Ethylene evolution by unaged papaya disks is inhibited potently by benzyl isothiocyanate. The compound inhibits production of ethylene by approximately 60% at a concentration of 0.046 mm. However, in aged papaya disks benzyl isothiocyanate causes no inhibition of ethylene production indicating that the compound inhibits the induction of the ethylene-producing system rather than the evolution of the gas per se. Even at a 2-fold higher concentration benzyl isothiocyanate has no effect on respiration of unaged papaya disks. It is proposed that benzyl isothiocyanate may act as an endogenous regulator of ethylene evolution in papaya fruit.     

Surface areas of naturally occurring lipid classes and the quantitative microdetermination of lipids

The surface area (A) of a lipid was directly proportional to the amount of lipid in a surface film (A = k micro moles) measured at constant surface pressure, temperature, and subphase composition. A surface area of 2300 cm(2)/ micro mole was obtained for cholesterol isolated from human adrenal and aorta and for cholesterol from hydrolysates of cholesteryl esters isolated from the same tissues. Unsaturated methyl esters that contained from one to four cis double bonds had the same surface area, 39.4 A(2)/molecule. As a consequence, naturally occurring triglyceride mixtures which had similar saturated-unsaturated fatty acid ratios had the same surface area, 6090 cm(2)/ micro mole. Naturally occurring phospholipid mixtures had the same surface area, 4590 cm(2)/ micro mole, and it appeared that the composition of these mixtures was regulated to control the physical properties of the mixtures. Surface area was much more sensitive than colorimetric procedures for the estimation of cholesterol and triglycerides. The surface area/molecule was a criterion of purity and an expanded surface area/molecule was an indication of autoxidation. Thus, surface area measurements were valuable for both the microdetermination and the characterization of lipid classes.     

Disparate data streams together yield novel survival estimates of Alaska-breeding Whimbrels

Survival estimates are critical components of avian ecology. In well-intentioned efforts to maximize the utility of one's research, survival estimates often derive from data that were not originally collected for survival assessments, and such post hoc analyses may include unintentional biases. We estimated the survival of Whimbrels captured and marked at two breeding sites in Alaska using divergent data streams that in isolation were subject to methodological biases. Although both capture sites were chosen to study the migration ecology of Alaska-breeding Whimbrels, maximizing the conservation value of the data we collected was obviously desirable. We used multi-year telemetry information to infer survival from one site (Colville River) and mark–resight techniques to estimate survival from a second site (Kanuti River). At Colville River, we could not feasibly include a control group of birds to assess potential survival effects of externally mounted transmitters, and at Kanuti River we were unable to account accurately for potential emigration events because we used resightings alone. We integrated these datasets in a Bayesian hierarchical framework, an approach that permitted insights across sites that moderated methodological biases within sites. Using telemetry enabled us to detect permanent emigration events from breeding sites in two of 10 birds, results that informed estimates for birds without tracking devices. These datasets yielded point estimates of true survival of Whimbrels from Colville River equipped with solar-powered satellite transmitters that were higher (0.83) than true survival estimates of Whimbrels from Kanuti River marked with leg flags alone (0.74) or equipped with surgically implanted satellite transmitters (0.50), but the 95% credible intervals on these estimates overlapped across groups. For species such as Whimbrels that are difficult and costly to study, combining information from disparate data streams allowed us to derive novel demographic estimates, an approach with clear application to other similar studies.     

metaGEM: reconstruction of genome scale metabolic models directly from metagenomes

Metagenomic analyses of microbial communities have revealed a large degree of interspecies and intraspecies genetic diversity through the reconstruction of metagenome assembled genomes (MAGs). Yet, metabolic modeling efforts mainly rely on reference genomes as the starting point for reconstruction and simulation of genome scale metabolic models (GEMs), neglecting the immense intra- and inter-species diversity present in microbial communities. Here, we present metaGEM (https://github.com/franciscozorrilla/metaGEM), an end-to-end pipeline enabling metabolic modeling of multi-species communities directly from metagenomes. The pipeline automates all steps from the extraction of context-specific prokaryotic GEMs from MAGs to community level flux balance analysis (FBA) simulations. To demonstrate the capabilities of metaGEM, we analyzed 483 samples spanning lab culture, human gut, plant-associated, soil, and ocean metagenomes, reconstructing over 14,000 GEMs. We show that GEMs reconstructed from metagenomes have fully represented metabolism comparable to isolated genomes. We demonstrate that metagenomic GEMs capture intraspecies metabolic diversity and identify potential differences in the progression of type 2 diabetes at the level of gut bacterial metabolic exchanges. Overall, metaGEM enables FBA-ready metabolic model reconstruction directly from metagenomes, provides a resource of metabolic models, and showcases community-level modeling of microbiomes associated with disease conditions allowing generation of mechanistic hypotheses.