Hemoglobins of the Lucina pectinata/bacteria symbiosis. II. An electron paramagnetic resonance and optical spectral study of the ferric proteins

We report an optical and EPR spectral study of three hemoglobins, Hb I, II, and III, from the gill of the clam Lucina pectinata. Hemoglobin I reacts much more avidly with hydrogen sulfide than do Hbs II and III. The proximal ligand to the heme iron of each hemoglobin is histidyl imidazole. The acid/alkaline transition of ferric Hb I occurs with pK 9.6; those of ferric Hbs II and III with pK 6.6 and 5.9, respectively. At their acid limits each ferric hemoglobin exists as aquoferric hemoglobin. Broadening of the g = 6 resonance suggests that the bound water enjoys great positional freedom. Ferric Hb I, at the alkaline limit (pH 11), exists as ferric hemoglobin hydroxide. Ferric Hbs II and III, at their alkaline limit (pH 7.5), each exist as equal mixtures of two species. The low spin species with optical maxima near 541 and 576 nm and g values of 2.61, 2.20, and 1.82, are identified as ferric hemoglobin hydroxide. The high spin species, with optical maxima near 486 and 603 nm and g values of 6.71, 5.87, and 5.06, resemble Dicrocoelium hemoglobin and hemoglobin MSaskatoon. Here we show that Hbs II and III resemble hemoglobin MSaskatoon in which a distal tyrosinate oxygen ligated to the ferric heme iron at alkaline pH is displaced by water at acid pH. The H2S product of ferric Hb I is identified as ferric hemoglobin sulfide.     

Scanning Electron Microscope Study of Neisseria gonorrhoeae

Morphological studies utilizing various microscopy techniques have aided in our understanding of the gonococcus and gonorrhea. In this study scanning electron microscopy was used to study differences in virulent (colony types 1 and 2) and avirulent (colony types 3 and 4) gonococci relative to colony appearance, patterns of growth in liquid media, and surface features of individual cocci. Colony types of virulent gonococci are smaller in diameter but have a higher evaluation than those of avirulent mutants. Colony type 2 has a convex undersurface that is associated with surface pitting of solid media. When the colonies are grown in liquid media, various degrees of autoagglutination are observed; this is most pronounced with type 2 and least evident with type 4. Although pili may be involved in this phenomena, other mechanisms must be employed, since type 3 gonococci that lack pili autoagglutinate. Pili are seen on types 1 and 2 and are absent from types 3 and 4. They appear as individual threads radiating from the bacteria or as bundles of pili attaching adjacent cocci. Another extracellular structure consists of small spherical bodies that can coat the bacteria surface, attach to pili, or exist free from other bacterial components. These spheres are least evident with type 4. The gonococcal surface is pebbly with multiple sulci.     

Biocœnotic studies on the parasites of two fir-and two oak-tortricids

Zusammenfassung Innerhalb eines Mischwaldbestandes der Vogesen wurde 1956 die Parasitierung der TortricidenChoristoneura (Cacoecia) murinana,Hb.,Eucosma (Semasia) rufimitrana H.s.,Archips (Cacoecia xylosteana l. undTortrix viridana l. vergleichend untersucht. Die innerhalb eines Parasitenkreises beobachteten Konkurrenzerscheinungen und die zwischender vier bearbeiteten Parasitenkomplexen gefundenen Wechselbeziehungen wurden qualitativ und quantitativ dargestellt (Abb. 2 und 3). Zwischen der theoretisch erwarteten Wirtswahl der untersuchten polyphagen Parasiten und den im Freiland beobachteten Verh?ltnissen ergab sich ein betr?chtlicher Unterschied. Die bei der Mehrzahl der gezüchteten Parasitenarten vorhandene potentielle Polyphagie kam zwar in der Erscheinung zum Ausdruck, dass hier vielfach 2 oder 3 der 4 geprüften Wirtsarten gleichzeitig befallen worden waren, aber das Schwergewicht der Parasitierung richtete sich immer nur gegen eine Wirtsart, obwohl eine ?r?umliche und zeitliche Koinzidenz? zwischen Wirt und Parasit (Thalenhorst 1951) auch in weiteren F?llen gegeben gewesen w?re. Eine solche beschr?nkte Wirtswahl kann, wie die durch Freilandversuche an der IchneumonideApechthis rufata gmel. gewonnenen Ergebnisse zeigen, durch einseitiges Anfliegen bestimmter Futterpflanzen der Wirte veranlasst sein. Der Vergleich zwischen der Wirtswahl in verschiedenen Beobachtungsgebieten weist schliesslich darauf hin, dass das Verhalten im Freiland bei manchen Parasitenarten weitgehen unberechenbar ist. Neben der Lebensweise der untersuchten Wirtsarten war auch die Hyperparasitierung für das Ausmass der durch die Parasiten verursachten Wirtsmortalit?t von Bedeutung. W?hrend die aus der Bioz?nose stammende HyperparasitengarniturC. murinana und die beiden Eichentortriciden in etwa gleichem Grad befield, wurde bei dem erstgenannten Wirt noch eine schwerezus?tzliche Beeinflussung der Larvenparasiten-Gruppe von seiten einiger, auch prim?r wirksamer Puppenparasiten festgestellt (Abb. 2). Diese Konkurrenzerscheinungen innerhalb des Parasitenkreises dürfte weitgehend für die Tatsache verantwortlich sein, dass beiC. murinana — im Gegensatz zu den Verh?ltnissen beiT. viridana undA. xylosteana — die Larvenparasitierung wesentlich unbedeutender ist als die Puppenparasitierung.      

Greenhouse gas emissions and global warming potential of traditional and diversified tropical rice rotation systems

Global rice agriculture will be increasingly challenged by water scarcity, while at the same time changes in demand (e.g. changes in diets or increasing demand for biofuels) will feed back on agricultural practices. These factors are changing traditional cropping patterns from double‐rice cropping to the introduction of upland crops in the dry season. For a comprehensive assessment of greenhouse gas (GHG) balances, we measured methane (CH₄)/nitrous oxide (N₂O) emissions and agronomic parameters over 2.5 years in double‐rice cropping (R‐R) and paddy rice rotations diversified with either maize (R‐M) or aerobic rice (R‐A) in upland cultivation. Introduction of upland crops in the dry season reduced irrigation water use and CH₄ emissions by 66–81% and 95–99%, respectively. Moreover, for practices including upland crops, CH₄ emissions in the subsequent wet season with paddy rice were reduced by 54–60%. Although annual N₂O emissions increased two‐ to threefold in the diversified systems, the strong reduction in CH₄ led to a significantly lower (P < 0.05) annual GWP (CH₄ + N₂O) as compared to the traditional double‐rice cropping system. Measurements of soil organic carbon (SOC) contents before and 3 years after the introduction of upland crop rotations indicated a SOC loss for the R‐M system, while for the other systems SOC stocks were unaffected. This trend for R‐M systems needs to be followed as it has significant consequences not only for the GWP balance but also with regard to soil fertility. Economic assessment showed a similar gross profit span for R‐M and R‐R, while gross profits for R‐A were reduced as a consequence of lower productivity. Nevertheless, regarding a future increase in water scarcity, it can be expected that mixed lowland–upland systems will expand in SE Asia as water requirements were cut by more than half in both rotation systems with upland crops.     

The molecular basis of cystathionine beta-synthase deficiency in Dutch patients with homocystinuria: effect of CBS genotype on biochemical and clinical phenotype and on response to treatment.

Homocystinuria due to cystathionine beta-synthase (CBS) deficiency, inherited as an autosomal recessive trait, is the most prevalent inborn error of methionine metabolism. Its diverse clinical expression may include ectopia lentis, skeletal abnormalities, mental retardation, and premature arteriosclerosis and thrombosis. This variability is likely caused by considerable genetic heterogeneity. We investigated the molecular basis of CBS deficiency in 29 Dutch patients from 21 unrelated pedigrees and studied the possibility of a genotype-phenotype relationship with regard to biochemical and clinical expression and response to homocysteine-lowering treatment. Clinical symptoms and biochemical parameters were recorded at diagnosis and during long-term follow-up. Of 10 different mutations detected in the CBS gene, 833T-->C (I278T) was predominant, present in 23 (55%) of 42 independent alleles. At diagnosis, homozygotes for this mutation (n=12) tended to have higher homocysteine levels than those seen in patients with other genotypes (n=17), but similar clinical manifestations. During follow-up, I278T homozygotes responded more efficiently to homocysteine-lowering treatment. After 378 patient-years of treatment, only 2 vascular events were recorded; without treatment, at least 30 would have been expected (P<.01). This intervention in Dutch patients significantly reduces the risk of cardiovascular disease and other sequelae of classical homocystinuria syndrome.