Commersonine,a new glycoalkaloid from two Solanum species

Selected plant introduction lines of S. chacoense and S. commersonii contain two major glycoalkaloids, demissine and a new compound called commersonine. In contrast, other plant introduction lines of S. chacoense contain only solanine and chaconine as the major glycoalkaloids. The isolation and characterization of the new glycoalkaloid is described.     

Sesquiterpene lactones — insect feeding deterrents in Vernonia

Larval feeding tests were run to determine the preference of six species of Lepidoptera for two species of Vernonia which produce sesquiterpene lactones and one which has lost the ability to produce these bitter principles. Significant differences between the feeding preferences of the insect species were observed. Further feeding tests were run with a Vernonia leaf powder medium to determine how interspecific chemical differences influenced these preferences. The sesquiterpene lactone, glaucolide-A, was found to reduce larval feeding when incorporated in a Vernonia powder-agar medium. The amount of insect feeding was inversely proportional to the concentration of glaucolide-A in the medium.     

THE DIATOMS OF TIMPANOGOS CAVE NATIONAL MONUMENT,UTAH

The diatom flora of the cavern system of Timpanogos Cave National Monument was investigated. Diatoms were found throughout the cave system and were distributed according to moisture and natural openings. Twenty-six species were identified and described, including eight not previously collected from caves and four new records for the state of Utah.     

THE KINETICS OF SENESCENCE

The course of decline of vitality with age due to the process of senescence, when not complicated by the process of growth, follows a simple exponential law; that is the degree of vitality or of senescence (defining vitality as the reciprocal of senescence) at any moment is, regardless of age, a constant percentage of the degree of vitality or senescence of the preceding moment. This exponential law is the same as the law of monomolecular change in chemistry. During the actively growing period of life the index of vitality rises, due to the process of growth and the course of vitality in the case when the growing period is included in the vitality curve, follows a rising and falling course. This rising and falling course may often be represented by an equation containing two exponential terms which is practically the equation used to represent the course of accumulation and disappearance of a substance as the result of two simultaneous consecutive monomolecular chemical reactions.     

The earthworm genus Pleionogaster (Clitellata: Megascolecidae) in southern Luzon, Philippines

An earthworm biodiversity survey of the Philippines has yielded 14 new species of the perichaetine megascolecid genus Pleionogaster, previously known from only a few species from scattered Philippine locations. Bicol, the southern peninsula of Luzon, has intact forests on several isolated volcanic peaks and other remote areas. Collections made in these forests yielded the following new species, here presented by type location: Mt. Malinao, Pleionogaster albayensis, P. bicolensis, P. castilloi, P. malinaoensis, P. tiwiensis; Mt. Isarog, P. ffitchae, P. isarogensis; Mt. Bulusan, P. bulusanensis, P. hongi, P. sorsogonensis; Catanduanes Island, P. nautsae, P. viracensis; Caramoan Peninsula, P. caramoanensis, P. nillosae. Most of the species were found only in the neighborhood of the type locality, but P. bicolensis occurs in two locations in northern Bicol. Intraspecific variation in P. castilloi was observed between northern and southern flanks of Mt. Malinao. The importance of several previously overlooked Pleionogaster traits is demonstrated by their homogeneity within species reported here.Full article published online at http://www.senckenberg.de/odes/06-08.htm.     

Ultrastructural carbohydrate cytochemistry of gastric epithelium

Synopsis On examination with ultrastructural methods for visualizing thevicinal glycols and acid groups of complex carbohydrates, the most superficial surface epithelium of the rat gastric corpus displayed biphasic mucous droplets consisting of a cortex of hexose-rich (i.e. periodate-reactive) neutral mucosubstance and an uncharacterized denser core plus monophasic droplets with the neutral mucosubstance. In many surface epithelial cells of the foveolae, the biphasic and monophasic droplets with the neutral mucosubstance intermingled in varying proportions with monophasic droplets showing uniform periodate reactivity, a variable degree of dialyzed ironbinding—demonstrative of acidic glycoconjugate, and high iron—diamine affinity—demonstrative of sulphomucin. Deep foveolar epithelium displayed only monophasic droplets, most of which contained acidic periodate-reactive complex carbohydrate. Underiying cells, designated isthmus cells, exhibited monophasic or occasional biphasic granules containing sulphated, hexose-rich mucosubstance. Nascent droplets or granules near the Golgi zone differed from the mature organelles in the distribution of the glycoconjugate. Mucous neck cells occupied a deeper stratum and displayed a uniform population of monophasic mucous droplets with a loose meshwork of neutral mucosubstance.Techniques for demonstrating hexoses ultrastructurally stained all Golgi cisternae in the mucigenic epithelium, showing increasing reactivity toward the maturing face. Distinctive cistemae with moderate reactivity in the Golgi complex of isthmus cells were interpreted as GERL. Acidic mucosubstances were visualized only in the inner, mature cisternae of the Golgi complex of cells storing acidic glycoconjugates, and not in cisternae interpretable as GERL.The apical plasmalemma of isthmus cells uniquely exhibited abundant sulphated glycoconjugate and that of parietal cells revealed a less prominent, periodic neutral mucosubstance. Lateral and basal plasmalemmae varied from unstained to slightly reactive; basement membranes showed moderate reactivity with methods for visualizing complex carbohydrates. Abundance of glycogen further characterized surface epithelial cells of the corpus and of some parietal cells     

Directed evolution reveals the mechanism of HitRS signaling transduction in Bacillus anthracis

Two component systems (TCSs) are a primary mechanism of signal sensing and response in bacteria. Systematic characterization of an entire TCS could provide a mechanistic understanding of these important signal transduction systems. Here, genetic selections were employed to dissect the molecular basis of signal transduction by the HitRS system that detects cell envelope stress in the pathogen Bacillus anthracis. Numerous point mutations were isolated within HitRS, 17 of which were in a 50-residue HAMP domain. Mutational analysis revealed the importance of hydrophobic interactions within the HAMP domain and highlighted its essentiality in TCS signaling. In addition, these data defined residues critical for activities intrinsic to HitRS, uncovered specific interactions among individual domains and between the two signaling proteins, and revealed that phosphotransfer is the rate-limiting step for signal transduction. Furthermore, this study establishes the use of unbiased genetic selections to study TCS signaling and provides a comprehensive mechanistic understanding of an entire TCS.