A conserved metalloprotease mediates ecdysis in Caenorhabditis elegans

Molting is required for progression between larval stages in the life cycle of nematodes. We have identified four mutant alleles of a <i>Caenorhabditis elegans</i> metalloprotease gene, <i>nas-37</i>, that cause incomplete ecdysis. At each molt the cuticle fails to open sufficiently at the anterior end and the partially shed cuticle is dragged behind the animal. The gene is expressed in hypodermal cells 4 hours before ecdysis during all larval stages. The <i>NAS-37</i> protein accumulates in the anterior cuticle and is shed in the cuticle after ecdysis. This pattern of protein accumulation places NAS- 37 in the right place and at the right time to degrade the cuticle to facilitate ecdysis. The nas-37 gene has orthologs in other nematode species, including parasitic nematodes, and they undergo a similar shedding process. For example, <i>Haemonchus contortus</i> molts by digesting a ring of cuticle at the tip of the nose. Incubating <i>Haemonchus</i> larvae in extracted exsheathing fluids causes a refractile ring of digested cuticle to form at the tip of the nose. When <i>Haemonchus</i> cuticles are incubated with purified NAS-37, a similar refractile ring forms. NAS-37 degradation of the <i>Haemonchus</i> cuticle suggests that the metalloproteases and the cuticle substrates involved in exsheathment of parasitic nematodes are conserved in free-living nematodes

Putting the UN SDGs on the map: The role of cartography in sustainability education

Editorial

A Status Report Lockheed Launch Vehicle

This paper discusses a new family of small and medium space launch vehicles being developed by Lockheed Missiles & Space Company, Inc. The development program will culminate in a demonstration launch in November 1994. The paper gives a brief background and gives the program status as of the date of this paper. Supporting graphics are included

Continuous Observation of Interference Fringes from Bose Condensates

We use continuous measurement theory to describe the evolution of two Bose condensates in an interference experiment. It is shown how the system evolves in a single run of the experiment into a state with a fixed relative phase, while the total gauge symmetry remains unbroken. Thus, an interference pattern is exhibited without violating atom number conservation.Comment: 4 pages, Postscrip

Dynamical density functional theory for the evaporation of droplets of nanoparticle suspension

We develop a lattice gas model for the drying of droplets of a nanoparticle suspension on a planar surface, using dynamical density functional theory (DDFT) to describe the time evolution of the solvent and nanoparticle density profiles. The DDFT assumes a diffusive dynamics but does not include the advective hydrodynamics of the solvent, so the model is relevant to highly viscous or near to equilibrium systems. Nonetheless, we see an equivalent of the coffee-ring stain effect, but in the present model it occurs for thermodynamic rather the fluid-mechanical reasons. The model incorporates the effect of phase separation and vertical density variations within the droplet and the consequence of these on the nanoparticle deposition pattern on the surface. We show how to include the effect of slip or no-slip at the surface and how this is related to the receding contact angle. We also determine how the equilibrium contact angle depends on the microscopic interaction parameters.Comment: 35 pages, 10 figure

Relative toxicity of gossypol enantiomers in laying and broiler breeder hens

Gossypol, a natural component of cottonseed meal, exists in positive (+) or negative (−) enantiomeric forms, and their levels and ratio could be altered by developing new genetic strains of cotton. Two experiments were conducted to determine the relative toxicity of the individual gossypol enantiomers in laying and broiler breeder hens. In the first experiment, 25 individually caged Hy-Line W-36 forty-three-week-old laying hens were fed a standard corn-soy diet supplemented with either no gossypol or the individual enantiomers at 200 and 400 mg/kg of diet for 20 d (5 hens/treatment). In the second experiment, 15 individually caged Cobb 500 fast-feathering 44-wk-old broiler breeder hens were fed a standard corn-soy-wheat middlings diet supplemented with either no gossypol or the individual enantiomers at 400 mg/kg of diet for 18 d (5 hens/treatment). In both experiments, feed intake, egg production, and egg weight were determined daily. All eggs were individually opened and scored for yolk discoloration. At the end of both experiments, several organ and tissue samples were collected for gossypol analyses. In both experiments, the addition of (+)-gossypol to the diet reduced egg production. Only laying and broiler breeder hens fed (+)-gossypol produced eggs with severe yolk discoloration (score ≥ 4). Total feed intake was lower (P < 0.05) in laying hens fed the 400 mg/kg level of (+)-gossypol compared with laying hens fed the other dietary treatments. In contrast, broiler breeder hens consumed less of the diet supplemented with (−)-gossypol. In both experiments, tissue accumulation of (+)-gossypol was higher than (−)-gossypol, with the exception of bile and excreta. The results suggest that in hens the ingestion of (+)-gossypol has a greater effect on egg yolk discoloration than the consumption of (−)-gossypol

Relative toxicity of gossypol enantiomers in broilers

Use of cottonseed meal in poultry diets has been avoided in large part because of fear of gossypol toxicity. Gossypol exists naturally as a mixture of 2 enantiomers that exhibit different biological activities. Two experiments were conducted to determine the relative toxicity of gossypol enantiomers on broilers. In the first experiment, 3-d-old broilers were fed a standard diet containing 0, 100, 200, 300, or 400 mg of gossypol from gossypol acetic acid per kilogram of diet from 3 to 42 d of age. This form of gossypol contains both enantiomers in an equimolar ratio. Each dietary treatment consisted of 6 replicate pens of 4 birds. In the second experiment, 3-dold broilers were divided into 15 pens of 4 birds each and fed a standard diet supplemented with either no gossypol or one of the gossypol enantiomers at 200 or 400 mg/kg of diet from 3 to 21 d of age. In both experiments, feed intake and BW gain were measured. In addi- (Key words: cottonseed meal, gossypol, gossypol enantiomer, broiler) 2005 Poultry Science 84:1376–1382 INTRODUCTION Cottonseed meal (CSM) could be an attractive alternative protein source for poultry diets, but concern over the presence of the potentially toxic agent, gossypol, has limited its use. Gossypol [1,1′,6,6′,7,7′-hexahydroxy-5,5′- diisopropyl-3, 3′-dimethyl-(2, 2′- binaphthalene)-8, 8′-dicarboxaldehyde] is a polyphenolic compound located in pigment glands that are distributed throughout the cotton plant. Gossypol is composed of 2 naphthalene rings with restricted rotation around the bond connecting the rings. As a result of this restricted rotation, gossypol occurs naturally as a mixture of 2 enantiomers [(+)- and (−)- 2005 Poultry Science Association, Inc. Received for publication February 7, 2005. Accepted for publication May 5, 2005. 1This research was supported in part by grant 2631RE683-118 from the Georgia Cotton Commission, Perry, GA. 2Mention of trade names or commercial products in this article is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the US Department of Agriculture. 3To whom correspondence should be addressed: [email protected]. 1376 tion, several organ and tissue samples were collected at 21 d (experiments 1 and 2) and 42 d (experiment 1) of age and analyzed for gossypol. In experiment 1, feed consumption and BW gain were reduced (P < 0.05) at 21 and 42 d for the birds fed the highest level of gossypol. The concentration of gossypol in the heart, kidney, and plasma were equivalent at 21 and 42 d of age. In experiment 2, total feed consumption was reduced only in birds consuming (−)-gossypol, but BW gains were lower for birds fed either enantiomer. However, (−)-gossypol was more detrimental to growth than (+)-gossypol. The liver had the highest tissue concentration of both enantiomers, and accumulation of (+)-gossypol was higher than (−)- gossypol in all tissues examined. No racemization of the enantiomers was apparent in the tissues analyzed. Our results indicated that both gossypol enantiomers were toxic to broilers but that (−)-gossypol was more harmful to efficient broiler production than (+)-gossypol

Three-Fluid Description of the Sympathetic Cooling of a Boson-Fermion Mixture

We present a model for sympathetic cooling of a mixture of fermionic and bosonic atomic gases in harmonic traps, based on a three-fluid description. The model confirms the experimentally observed cooling limit of about 0.2 T_F when only bosons are pumped. We propose sequential cooling -- first pumping of bosons and afterwards fermions -- as a way to obtain lower temperatures. For this scheme, our model predicts that temperatures less than 0.1 T_F can be reached.Comment: 9 pages, 6 figure