The proteasome of Mycobacterium tuberculosis is required for resistance to nitric oxide

The production of nitric oxide and other reactive nitrogen intermediates (RNI) by macrophages helps to control infection by Mycobacterium tuberculosis (Mtb). However, the protection is imperfect and infection persists. To identify genes that Mtb requires to resist RNI, we screened 10,100 Mtb transposon mutants for hypersusceptibility to acidified nitrite. We found 12 mutants with insertions in seven genes representing six pathways, including the repair of DNA (uvrB) and the synthesis of a flavin cofactor (fbiC). Five mutants had insertions in proteasome-associated genes. An Mtb mutant deficient in a presumptive proteasomal adenosine triphosphatase was attenuated in mice, and exposure to proteasomal protease inhibitors markedly sensitized wild-type Mtb to RNI. Thus, the mycobacterial proteasome serves as a defense against oxidative or nitrosative stress.     

A Burkholderia pseudomallei toxin inhibits helicase activity of translation factor eIF4A

The structure of BPSL1549, a protein of unknown function from Burkholderia pseudomallei, reveals a similarity to Escherichia coli cytotoxic necrotizing factor 1. We found that BPSL1549 acted as a potent cytotoxin against eukaryotic cells and was lethal when administered to mice. Expression levels of bpsl1549 correlate with conditions expected to promote or suppress pathogenicity. BPSL1549 promotes deamidation of glutamine-339 of the translation initiation factor eIF4A, abolishing its helicase activity and inhibiting translation. We propose to name BPSL1549 Burkholderia lethal factor 1.     

From a single-band metal to a high-temperature superconductor via two thermal phase transitions

The nature of the pseudogap phase of cuprate high-temperature superconductors is a major unsolved problem in condensed matter physics. We studied the commencement of the pseudogap state at temperature T* using three different techniques (angle-resolved photoemission spectroscopy, polar Kerr effect, and time-resolved reflectivity) on the same optimally doped Bi2201 crystals. We observed the coincident, abrupt onset at T* of a particle-hole asymmetric antinodal gap in the electronic spectrum, a Kerr rotation in the reflected light polarization, and a change in the ultrafast relaxational dynamics, consistent with a phase transition. Upon further cooling, spectroscopic signatures of superconductivity begin to grow close to the superconducting transition temperature (T(c)), entangled in an energy-momentum-dependent manner with the preexisting pseudogap features, ushering in a ground state with coexisting orders.     

Predicting a human gut microbiota's response to diet in gnotobiotic mice

The interrelationships between our diets and the structure and operations of our gut microbial communities are poorly understood. A model community of 10 sequenced human gut bacteria was introduced into gnotobiotic mice, and changes in species abundance and microbial gene expression were measured in response to randomized perturbations of four defined ingredients in the host diet. From the responses, we developed a statistical model that predicted over 60% of the variation in species abundance evoked by diet perturbations, and we were able to identify which factors in the diet best explained changes seen for each community member. The approach is generally applicable, as shown by a follow-up study involving diets containing various mixtures of pureed human baby foods.     

Soft palate cyst in a cat

A 17-month-old cat presented for frequent swallowing, occasional cough and stertor. Radiographic evaluation revealed a soft tissue mass at the level of the soft palate. Oral examination revealed a soft tissue mass within the soft palate. Surgical resection was performed. Histopathology was consistent with a large developmental cyst. Following surgical management the cat has remained clinically free of signs for 2 months.     

Dynamic plant uptake model applied for drip irrigation of an insecticide to pepper fruit plants

BACKGROUND: Drip application of insecticides is an effective way to deliver the chemical to the plant that avoids off‐site movement via spray drift and minimizes applicator exposure. The aim of this paper is to present a cascade model for the uptake of pesticide into plants following drip irrigation, its application for a soil‐applied insecticide and a sensitivity analysis of the model parameters. RESULTS: The model predicted the measured increase and decline of residues following two soil applications of an insecticide to peppers, with an absolute error between model and measurement ranging from 0.002 to 0.034 mg kg fw^?1. Maximum measured concentrations in pepper fruit were approximately 0.22 mg kg fw^?1. Temperature was the most sensitive component for predicting the peak and final concentration in pepper fruit, through its influence on soil and plant degradation rates. CONCLUSION: Repeated simulations of pulse inputs with the cascade model adequately describe soil pesticide applications to an actual cropped system and reasonably mimic it. The model has the potential to be used for the optimization of practical features, such as application rates and waiting times between applications and before harvest, through the integrated accounting of soil, plant and environmental influences. Copyright © 2011 Society of Chemical Industry     

Evaluation of Meat and Bone Meal in Practical Diets Fed to Juvenile Hybrid Striped Bass Morone chrysops×M. saxatilis

Juvenile hybrid striped bass ( Morone chrysops × M. saxatilis ) were fed one of eight diets to evaluate meat and bone meal as a source of crude protein and essential amino acids. Diets contained either 0, 15, 20, 25, 30, 35, 40 or 45% meat and bone meal substituted for an isonitrogenous amount of soybean meal and fish meal. All diets were fed for 7 wk, followed by a 2-wk digestibility trial. Mean consumption, weight gain, and feed conversion ratio were not significantly affected by addition of meat and bone meal into diets. Intraperitoneal and liver lipid concentrations were not significantly affected by meat and bone meal. Fillet proximate composition was not significantly different among treatments. Apparent crude protein, phosphorus, and amino acid availabilities were significantly lower in fish fed 45% meat and bone meal compared to fish fed 30% and lower concentrations and generally lower in fish fed greater than 30% meat and bone meal. Based on these data, it appears meat and bone meal can be used as the primary source of crude protein and essential amino acids in practical growout diets for hybrid striped bass, comprising as much as 45% of the diet. Nutrient availability values were lower in fish fed greater than 30% meat and bone meal and may restrict usage in some applications.     

The effect of the duration and type of stress on some serum enzyme levels in pigs.

The effects of blood sampling from the ear vein, jugular vein and collection on exsanguination, on serum CK, LDH, GOT and PK activities were investigated. The activities of LDH and PK were higher in ear vein vena cava samples. The effect of pre-slaughter handling was also investigated. In general there was a significant progressive increase in serum enzyme activities from farm to slaughter, although the magnitude of the change varied for different enzymes.     

Anterior pituitary concentrations of gonadotropins, GnRH-receptors and ovarian characteristics following early weaning in beef cows

Endocrine changes in the hypophyseal-ovarian axis associated with early calf removal were investigated in anestrous beef cows. Tissues were collected and analyzed from multiparous beef cows slaughtered at O (n = 8), 36 (n = 8) or 72 h (n = 8) after calf removal during the fifth week after calving. Cows that exhibited estrus; had postmortem signs of a recent ovulation or had serum concentrations of luteinizing hormone (LH) indicative of an ovulatory surge, were excluded from the analysis. Five control cows that were not slaughtered exhibited estrus from 30 to 84 h after calf removal. Seven additional cows were continuously kept with their calves and did not exhibit estrus until 72 +/- 9 d after calving. Serum concentrations of estradiol-17 beta (estradiol) averaged 8.2 +/- 1.7, 7.5 +/- 2.0 and 9.1 +/- 1.5 pg/ml at 0, 36 and 72 h, respectively, but they averaged 22.8 +/- 4.7 pg/ml prior to estrus in control cows. Therefore, observations were assumed to represent events that occur prior to the rise in serum concentrations of estradiol that occurs during proestrus. Volume of fluid from the largest ovarian follicle tended to be greater (P less than .10) at 72 h (1.5 +/- .2 ml) than at 0 h (1.1 +/- .1 ml) or 36 h (1.0 +/- .1 ml). Follicular-fluid concentrations of estradiol, but not progesterone, were positively correlated (P less than .01) with follicular volume. However, numbers of small (less than 100 microliters), medium (100 to 400 microliters) and large follicles (greater than 400 microliters) as based on fluid volume, as well as follicular-fluid concentrations of estradiol and progesterone, did not differ among treatment groups.(ABSTRACT TRUNCATED AT 250 WORDS)