Allescheria boydii and Aspergillus fumigatus Skin Test Antigens

May, Lewis K. (Woman's Medical College of Pennsylvania, Philadelphia), Ralph A. Knight, and H. William Harris. Allescheria boydii and Aspergillus fumigatus skin test antigens. J. Bacteriol. 91:2155-2157. 1966.-Protein and polysaccharide fractions were extracted from culture filtrates of Allescheria boydii and Aspergillus fumigatus by the methods of Seibert and of Heidelberger, and injected intradermally into guinea pigs previously infected with these fungi. The diameter of erythema and induration was determined at 8, 24, and 48 hr. The protein and polysaccharide antigens yielded specific skin reactions in homologously infected guinea pigs. Erythema appeared at 8 hr with both the protein and polysaccharide antigens. At this time, the polysaccharide skin tests showed erythema and a central blanched wheal. A similar wheal was not observed with the protein. The erythema of the polysaccharide reaction began fading at 24 hr, whereas the protein reaction remained unchanged through 48 hr with both antigens. In guinea pigs, the area of erythema was more constant and thus easier to measure than was induration.     

Beneficial arthropod behavior mediated by airborne semiochemicals. VIII. Learning of host-related odors induced by a brief contact experience with host by-products inCotesia marginiventris (Cresson), a generalist larval parasitoid

Females of Cotesia marginiventris(Cresson), a generalist larval parasitoid, were observed to respond to host related odors in a four-arm olfactometer. The females were significantly more responsive to the odors after a brief contact experience with host-damaged leaves contaminated with host by products. During the experience, actual encounters with hosts were not required to improve subsequent responses to host-related odors. The response to odors of the plant-host complex with which parasitoids had experience was significantly higher than the response to odors of an alternative plant-host complex. This suggests that the experience effect is due, at least partly, to associative learning. We suspect that females of this generalist parasitoid, as was recently found for those of a specialist, recognize specific semiochemicals when they contact frass of suitable host larvae. The parasitoids, subsequently, associate the surrounding odors with the possible presence of hosts, and use these odors as cues in their search for more hosts. This could be an important component in the host-searching behavior of many parasitoids.Mention of a proprietary product does not constitute an endorsement or the recommendation for its use by the USDA.     

Charybdotoxin blocks voltage-gated K+ channels in human and murine T lymphocytes

A variety of scorpion venoms and purified toxins were tested for effects on ion channels in human T lymphocytes, a human T leukemia cell line (Jurkat), and murine thymocytes, using the whole-cell patch-clamp method. Nanomolar concentrations of charbdotoxin (CTX), a purified peptide component of Leiurus quinquestriatus venom known to block Ca2+-activated K+ channels from muscle, blocked "type n" voltage-gated K+ channels in human T lymphoid cells. The Na+ channels occasionally expressed in these cells were unaffected by the toxin. From the time course of development and removal of K+ channel block we determined the rates of CTX binding and unbinding. CTX blocks K+ channels in Jurkat cells with a Kd value between 0.5 and 1.5 nM. Of the three types of voltage-gated K+ channels present in murine thymocytes, types n and n' are blocked by CTX at nanomolar concentrations. The third variety of K+ channels, "type l," is unaffected by CTX. Noxiustoxin (NTX), a purified toxin from Centruroides noxius known to block Ca2+-activated K+ channels, also blocked type n K+ channels with a high degree of potency (Kd = 0.2 nM). In addition, several types of crude scorpion venoms from the genera Androctonus, Buthus, Centruroides, and Pandinus blocked type n channels. We conclude that CTX and NTX are not specific for Ca2+ activated K+ channels and that purified scorpion toxins will provide useful probes of voltage-gated K+ channels in T lymphocytes. The existence of high-affinity sites for scorpion toxin binding may help to classify structurally related K+ channels and provide a useful tool for their biochemical purification.     

Selection of Astaxanthin-Overproducing Mutants of Phaffia rhodozyma with beta-Ionone

beta-Ionone, an end ring analog of beta-carotene, inhibits astaxanthin production in the red yeast Phaffia rhodozyma. Astaxanthin-overproducing mutants of this yeast are easily spotted on beta-ionone-containing yeast malt agar plates. beta-Ionone appears to block astaxanthin synthesis at the beta-carotene level.     

The effects of host distributional patterns on parasite transmission: Aedes aegypti larvae and Plagiorchis noblei Cercariae

The effects of distributional patterns of the host on the acquisition of Plagiorchis noblei cercariae by Aedes aegypti larvae were determined. Mosquito larvae that were allowed to disperse were more susceptible to infection than confined larvae. Because these mosquito larvae are known to aggregate in light and disperse in darkness, they are more likely to acquire P. noblei infections at night. The timing of cercarial emergence in relation to the distributional patterns of the mosquito host is discussed.     

Effect of acute nutritional deprivation on diaphragm structure and function

The influence of 90 h of acute nutritional deprivation (ND) on the cross-sectional areas of muscle fibers and the contractile and fatigue properties of the adult rat diaphragm were determined. Isometric contractile properties and fatigue resistance of the diaphragm were measured by means of an in vitro nerve-muscle strip preparation. Contractions were evoked by using phrenic nerve stimulation (left hemidiaphragm) or direct muscle stimulation (right hemidiaphragm) in the presence of curare. Acute ND resulted in a 20% reduction in body weight. No significant decrements in diaphragm or soleus weights were noted in the ND animals compared with controls (CTL), whereas the weight of the medial gastrocnemius was reduced by 20% in the ND animals. Peak twitch and tetanic tensions (normalized for the weight of the diaphragm strip) were not reduced in ND compared with CTL animals after either nerve or muscle stimulation. The fatigue index of the diaphragm was significantly reduced in ND animals only after nerve stimulation. After the fatigue test, there was rapid recovery of the additional fatigue noted with nerve stimulation. The proportions of type I and II muscle fibers of the diaphragm were similar in the CTL and ND animals. No differences in diaphragm cross-sectional areas were noted for either type I or II muscle fibers in the CTL and ND animals. It is concluded that acute ND has no effect on diaphragm contractility or morphometry and only an inconsequential influence on diaphragm fatigue.     

Motion behavior of nauplii and early copepodid stages of marine planktonic copepods

The goal of this study was to quantify periods of activity andvelocities of late naupliar and early copepodid stages of planktoniccopepods occurring regularly on the southeastern continentalshelf of the USA. We obtained quantitative information on eightspecies, including adult females of Oithona plumifera. All studieswere conducted at food concentrations near or above satiationlevels. Activities ranged from 0.85% (adult females of O.plumifera)to 100% of time (nauplii and copepodids of various calanoidspecies). Motion velocities (excluding escape motion) coveredmore than one order of magnitude: from 0.39 mm s^–1 fornauplii of Temora stylifera to 5.24 mm s^–1 for naupliiof Oncaea mediterranea. Ranges of activities of species rangefrom occasional for early juveniles to adult females of O.plumiferato 100% for the same range of T.stylifera, the latter creatinga feeding current from N III onwards, the former not at all.Of notable interest is Centropages velificatus which moves intermittentlyas a late nauplius, continuously as an early copepodid and intermittentlyas an adult. All observed calanoid late nauplii and copepodidsmove in three dimensions, excluding copepodids of the shelfbreak/oceanicParacalanus aculeatus. The results indicate not only significantdifferences in motion behavior between cyclopoids and calanoids,but also between calanoid species. Yet, some calanoid speciesshow little ontogenetic changes at all.