Wood excavations of three species of subterranean termites

We compared the feeding excavations on wood blocks of three species of subterranean termites, Coptotermes formosanus Shiraki, Reticulitermes flavipes (Kollar), and R. virginicus (Banks). Feeding rate followed the order C. formosanus > R. flavipes > R. virginicus. Wood surface area (mm²) exposed per unit feeding was higher for C. formosanus and R. flavipes than for R. virginicus. This was caused by the tendency of C. formosanus and R. flavipes to make internally penetrating tunnels, thereby increasing surface area, whereas R. virginicus made trough- and bowl-like depressions on the outside of blocks, sometimes decreasing the size of blocks outwardly without a corresponding high increase in surface area typical with the tunnels of the other species. Consequently, wood surface area was sometimes reduced, rather than increased as a result of feeding by R. virginicus. Different patterns of wood excavation suggest that these termites have divergent roles in wood decay processes.

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Résumé Les organismes pionniers qui modifient le bois et le rendent acceptable par les insectes qui le perforent sont généralement des champignons du bois pourri. Cependant, une fois que les termites ou autres insectes perforant le bois ont pénétré, leurs galeries favorisent les bactéries fixatrices d'azote, permettent l'invasion d'autres organismes décomposeurs, et de ce fait régularisent la décomposition du bois (Ausmus, 1977). L'exposition de la surface à l'intérieur des perforations jouant un rôle très important dans le processus de pourrissement, il est souhaitable de pouvoir quantifier la surface des galeries dues à l'alimentation des termites. Une courbe type permettant de prédire l'aire de la surface perforée a été construite en perçant 109 morceaux de bois de trous cylindriques de différents diamètres, en calculant l'aire de la surface des morceaux de bois, en appliquant et pesant une couche de vernis pour bois au polyuréthane, et en divisant la masse de polyuréthane par l'aire de la surface. Le modèle prédictif qui en découle est: Y=0,01443×-3,51825 (P=0,0001; r=0,68), y étant la masse de polyuréthane (en g) et x la surface (en mm²) du morceau de bois. En traitant de la même façon au polyuréthane les morceaux de bois perforés par les termites, nous pourrions déduire leur surface.Une expérience a été effectuée avec 3 espèces de rhinotermitides,- Coptotermes formosanus Shiraki, Reticulitermes flavipes (Kollar) et R. virginicus (Banks). Des groupes de chaque espèce se sont alimentés pendant 11 ou 12 jours sur des morceaux de bois non contaminés par des champignons. Nous avons déterminé la survie, la consommation, la modification de la surface du morceau de bois (par utilisation du modèle prédictif) et le changement de surface par terminte.La survie est la même, mais la consommation est dans l'ordre suivant: C. formosanus > R. flavipes > R. virginicus. L'aire de la surface exposée par unité d'alimentation était plus élevée pour C. formosanus et R. flavipes que pour R. virginicus (Tab. 1). Ceci est dû à la tendance de C. formosanus et R. flavipes de creuser des galeries vers l'intérieur, tandis que R. virginicus fait des cuvettes à la surface du bois. Les attaques superficielles de R. virginicus réduisent parfois le volume du morceau de bois sans accroître proportionnellement la surface comme le font les espèces creusant des galeries. Ainsi, avec R. virginicus la surface peut être réduite au lieu d'augmenter. Des différences entre colonies s'observent avec toutes les variables (Tab. 2).Nos résultats suggèrent que C. formosanus et R. flavipes contribuent plus que R. virginicus à exposer le bois aux autres organismes décomposeurs. Cependant, ces résultats peuvent être modifiés par un conditionnement préalable du bois par des champignons.

     

Juvenile hormone esterases of Lepidoptera

Summary The juvenile hormone esterase (JHE) titer was measured during the last larval instar of 11 species of Lepidoptera (Pieris rapae, Junonia coenia, Danaus plexippus, Hemileuca nevadensis, Pectinophora gossypiella, Spodoptera exigua, Orgyia vetusta, Ephestia elutella, Galleria mellonella, Manduca sexta andEstigmene acrea). All species had a peak of JHE at or near the time of wandering. The peak activity at this time ranged from 0.8 to 388 nmoles JH III cleaved/min·ml. All species exceptJ. coenia had a second peak of JHE during the late prepupal stage. The height of the second peak ranged from 0.4 to 98.4 nmoles/min·ml. However, there was no apparent correlation between size of the first and second JHE activity peaks for the lepidopteran species examined. There was an apparent relationship between the height of the first and second JHE peaks and reports on titer of JH just prior to these peaks. These data support, with some qualifications, the extension of developmental information obtained on several well studied species to a variety of Lepidoptera.Abbreviations JH juvenile hormone - JHE juvenile hormone esierase - PTTH prothoracotropic hormone - R _o -10-3108 1-(4-ethylphenoxy)-6,7-epoxy-3-ethyl-7-methylnonane     

Magnitude of colonization and sepsis by group B streptococci in newborn infants

Infants admitted to the Neonatal Intensive Care Unit at Tampa General Hospital, Tampa, Florida, were cultured for group B streptococci (GBS). Culture swabs were quantified for GBS to determine the magnitude of colonization in infected infants. Thirty-seven (17%) of the 217 infants cultured were positive for GBS. Six of these colonized infants developed sepsis, with blood cultures positive for GBS. Septic infants generally were colonized by large numbers of GBS (10⁵ bacteria/culture swab) at two or more external skin sites, in comparison to aseptic infants, who were lightly colonized with GBS. The data suggest a possible correlation between magnitude of colonization by GBS at external skin sites and development of GBS sepsis in newborn infants.     

Immunocytochemical demonstration of nerve growth factor and histofluorescence of catecholaminergic nerves in the salivary glands of diabetic mice

Summary Nerve growth factor (NGF) was localized in the submandibular, sublingual, and parotid salivary glands of male and female diabetic mice and their normal littermates by immunoperoxidase staining usingp-phenylenediamine-pyrocatechol as a chromogen for the cytochemical demonstration of peroxidase activity. In the normal male submandibular gland, immunoreactive NGF was localized in the apical regions of granular, intercalated and collecting duct cells, while in the normal female submandibular gland, NGF was present throughout the cytoplasm of granular duct cells. The localization of NGF in the diabetic male and female submandibular glands was similar and resembled that of the normal female. NGF immunoreactivity was also observed in the striated duct cells in the sublingual and parotid glands of all four types of mice.The sympathetic innervation of the submandibular glands of normal and diabetic mice was demonstrated using glyoxylic acid-induced histofluorescence. The pattern of sympathetic innervation and the intensity of catecholamine fluorescence was consistently different in the four types of mice. In the normal male submandibular gland the fluorescence was very intense, particularly in nerves adjacent to the granular ducts. In the normal female submandibular gland, the fluorescence was weak, while in the diabetic male and female the fluorescence was moderate.The correlation between the intensity of the immunocytochemical staining for NGF and the catecholamine fluorescence adjacent to the granular ducts suggests a trophic influence of the NGF-containing granular ducts on their sympathetic innervation.     

Identification of bacterial chemoattractants for oyster (Crassostrea virginica) hemocytes

The cytoplasmic and cell wall components of the Gram-positive bacterium Bacillus megaterium and the cytoplasmic and cell envelope components of the Gram-negative bacterium Escherichia coli were assayed for chemotactic activity for the hemocytes of Crassostrea virginica. The cellular components were separated by differential centrifugation and gel filtration was used to determine the approximate molecular weights of the chemoattractant molecules. Active fractions were assayed for glycoproteins and lipoproteins. As a result, it is known that hemocytes are chemotactically attracted to proteins of approximately 10,000 daltons which are associated with the cell wall of B. megaterium and the cell envelope of E. coli.     

Deamination of 5-Hydroxytryptamine by Both Forms of Monoamine Oxidase in the Rat Brain

Abstract: K _m and V _max values of monoamine oxidase (MAO) A and B towards 5-hydroxytryptamine were determined for rat brain homogenates after the in vitro inhibition of one of the two forms by the selective inhibitors clorgyline and l -deprenyl. K _m values of 178 and 1170μ m , and V _max values of 0.73 and 0.09 nmol·mg protein⁻¹·min⁻¹ towards 5-hydroxytryptamine were found for MAO-A and -B, respectively. The K ₁ for 5-hydroxytryptamine as a competitive inhibitor of β-phenethylamine oxidation by MAO-B was found to be 1400 μm. The significance of these findings is discussed.     

Relation between diameter and flow in branches of the bronchial tree

Two methods are described for calculating the value of the exponentx in the equation flow =k×diameter ^x , as pertaining to a branch of the bronchial tree. In the lungs from three humans, two dogs, one hamster, and one rat mean values ofx between 2.419 and 2.903 were found. They lie within the range of 2.333 to 3.0 predicted by the analysis of Uylings (Bull. Math. Biol. 39, 501–519, 1977).     

Organic acids from the anaerobic decomposition of Agropyron repens rhizomes

Phytotoxicity originating from the anaerobic decomposition of couch grass rhizomes has been studied. Short chain aliphatic (acetic, propionic and butyric) acids appear to be mainly responsible but hexanoic, succinic, phenylacetic, cinnamic, p-coumaric, 4-hydroxyphenylpropionic and 3,4-dihydroxyphenylpropionic acids are also present in the phytotoxic solutions formed during the decomposition.