Decreased Exopolysaccharide Synthesis by Anaerobic and Symbiotic Cells of Bradyrhizobium japonicum

Experiments were conducted to determine whether symbiotic bacteroids of Bradyrhizobium japonicum produce exopolysaccharide within soybean (Glycine max [L.] Merr. cv `Lee 74') nodules. B. japonicum strains RT2, a derivative of USDA 110 with resistance to streptomycin and rifampicin, and RT176-1, a mutant deficient in exopolysaccharide synthesis, were used. Although aerobically cultured RT2 produced 1550 micrograms of exopolysaccharide per 10¹⁰ cells, root nodules formed by RT2 contained only 55.7 micrograms of polysaccharide per 10¹⁰ bacteroids, indicating that little exopolysaccharide synthesis occurred within the nodules. The polysaccharide level of RT2 nodules was about equal to that of nodules containing the exopolysaccharide mutant RT176-1 (61.0 micrograms per 10¹⁰ bacteroids). Gas chromatographic analysis showed that the sugar composition of polysaccharide from nodules of RT2 or RT176-1 was almost the same as that of polysaccharide from unnodulated root tissue, but differed strikingly from that of rhizobial exopolysaccharide from aerobic cultures. Thus, the host plant and not the bacteroids was probably the source of most or all of the polysaccharide in the nodule extracts. Also, bacteroids from nodules failed to bind soybean lectin, confirming the absence of an exopolysaccharide capsule.     

Extraction and Partial Characterization of Enkephalin-Like Peptides from Splanchnic Nerve

A method is described for the extraction of enkephalin-like peptides from peripheral nerve using chloroform and acidic methanol to facilitate a differential extraction of peptides and lipid. Porcine splanchnic nerve contains enkephalin-like peptides in low amounts compared to porcine adrenal medulla and striatum. Gel filtration chromatography reveals the presence of enkephalin-like peptides in both processed and cryptic forms. This is the first reported isolation and partial characterization of these peptides in splanchnic nerve. The presence of these peptides in this nerve provides support for the contention that the splanchnic nerve can modulate catecholamine release from the adrenal medulla through an effect on opiate receptors located on chromaffin cells.     

A simple algal production system designed to utilize the flashing light effect

Arrays of foils similar in design to airplane wings have been placed in an algal culture flume to create systematic mixing. Vortices are produced in the culture due to the pressure differential created as water flows over and under the foils. In a flume having a flow rate of 30 cm/s, the foil arrays produced vortices with rotation rates of ca. 0.5-1.0 Hz. This rotation rate is satisfactory to take advantage of the flashing light effect if the culture is sufficiently dense. Solar energy conversion efficiencies in an experimental culture of P. tricornutum increased 2.2-2.4 fold with the foil arrays in place versus controls with no foil arrays and solar energy conversion efficiencies averaged 3.7% over a three-month period. Five-day running means of solar energy conversion efficiencies reached as high as 10% during the three-month period. The use of foil arrays appears to be an effective and inexpensive way to utilize the flashing light effect in a dense algal culture system.     

Effects of negative air ions,noise, sex and age on maze learning in rats

An equal number of male and female rats of the King-Holtzman hybrid breed, divided into two age groups (group A₁ : 21–30 days old and group A₂ : 90–100 days old), were exposed to two levels of noise: N₀ = 30 db and N₁ = 90 db, (Ref. 0.0002μ bar), and three levels of negative air ions: I_O = no measurable ion concentration, I₁ = 7 × 10⁶ ions/cm³ and I₂ = 7 × 10⁷ ions/cm³. Time and error scores of 240 rats running a modified Lashley left-right maze with an escape-from-water motive served as criteria. A randomized complete blocks design with replications (2×3×2×2×10) was selected for treatment by analysis of variance. The results indicate that (a) the males show significantly lower error score in negatively ionized air; and (b) the females swim significantly faster than males under all investigated conditions with no apparent effect of noise or ions on their performance.

---

Zusammenfassung Eine gleiche Anzahl m?nnlicher und weiblicher Ratten (n = 120) des King-Holtzman Stammes, unterteilt in 2 Altersgruppen (21–30 und 90–100 Tage) wurden zwei Ger?uschintensit?ten (30 db und 90 db) und 3 Konzentrationen negativer Luftionen I₀: nicht messbar niedrig, I₁:7×10⁶, I₂:7×10⁷ Ionen/cm³ ausgesetzt. Die Wirkung wurde geprüft an der Schwimmzeit und der Anzahl Fehler der Tiere im Lasley-Links-Rechts-Labyrinth. Das Motiv zum Schwimmen war, aus dem Wasser zu entkommen. Die Auswertung durch Varianzanalyse erfolgte unter Nachbildung randomisierter kompletter Blockentwürfe. Die Ergebnisse zeigen, dass (a) die M?nnchen bei negativ ionisierter Luft signifikant weniger Fehler machten und (b) die Weibchen unter allen Bedingungen schneller schwammen als die M?nnchen, ohne dass das L?rmniveau oder die Luftionisation darauf einen Einfluss hatten.

---

Resume Un nombre égal de rats males et femelles (120 de chaque) de la race King-Holtzman futdivisé en deux groupes d'age (21 à 30 jours et 90 à 100 jours). Ils furent exposés à 2 intensités auditives (30 et 90 db) et à 3 concentrations d'ions négatifs: I₀ non mesurables (faible), I₁ : 7 × 10⁶ et I₂: 7 × 10⁷ ions/cm³. Les effets d'un tel traitement furent examinés au moyen de deux critères: le temps pris pour sortir de l'eau et le nombre de fautes commises dans un labyrinthe droitegauche de Laslay. Pour l'analyse des variances, on a adopté une répartition due au hasard avec répétitions (2×3×2×2×10). On peut en conclure que: (a) les males font moins d'erreurs dans l'air ionisé négativement et cela de fa?on significative et (b) les femelles ont nagé plus vite que les males dans toutes les conditions de l'essai. Ni le bruit ni le degré d'ionisation ne semblent avoir d'influence sur leur comportement.

---

---

This study was supported in part by a grant from the Faculty Research Fund of the University of Oklahoma.     

Effects of direct electric fields,noise, sex and age on maze learning in rats

Equal numbers of male and female rats of the King-Holtzman hybrid breed, divided into two age groups (group A₁: 21–30 days old and group A₂: 90–100 days old), were exposed to two levels of noise: N₀ = 30 db and N₁ = 90 db, (ref. 0.002µbar), and three levels of direct electric field intensities: E₀ = electric field strength of zero; E₁ = 1,600 v/m; and E₂ = 16,000 v/m. Time and error scores of 240 rats running a modified Lashley left-right maze with an escape-from-water motive served as criteria. A randomized complete blocks design with replications (2 × 3 × 2 × 2 × 10) was selected for treatment by analysis of variance. The results indicate that (a) adult rats pre-exposed to electric fields showed significantly lower error scores than young rats, regardless of sex or the noise condition; (b) after exposure to electric fields all rats swam faster than their controls; (c) after exposure to noise females showed significantly higher time scores than males under the same conditions, regardless of age; and (d) when subjected to the combined effect of electric fields and noise males showed significantly lower time scores than females under the same conditions, regardless of age.

---

Zusammenfassung Zwei Altersgruppen (21–30 und 90–100 Tage) männlicher and weiblicher Ratten des King-Holtzman-Stammes wurden 2 Lärmintensitäten (30 db und 90 db) und 3 elektrischen Feldstärken (0, 1.600 v/m und 16.000 v/m) ausgesetzt und die Lernfähigkeit beim Schwimmen im modifizierten Lashley linksrechts Maze geprüft. Das Kriterium waren die Zeit und die Anzahl Fehler bei dem Versuch aus dem Wasser zu entkommen. Auswertung der Messungen durch Varianzanalyse unt er Nachbildung kompletter Blockentwürfe. Die Ergebnisse zeigen: (a) Erwachsene Ratten, die vorher elektrischen feldern ausgesetzt wurden, wiesen signifikant weniger fehler auf als junge Ratten, unabhängig vom Geschlecht und Lärmbedingungen; (b) nach der Exponierung in elektrischen Feldern schwammen alle Ratten schneller als die unbehandelten Kontrollen; (c) nach Lärmeexponierung zeigten weibliche Ratten signifikant höhere Trefferzeiten als Männchen unter den gleichen Bedingungen ohne Beziehung zum Alter und (d) bei gleichzeitiger Anwendung von elektrischen Feldern und Lärm wiesen die Männchen niedrigere Trefferzeiten auf als die Weibchen. Alter spielte dabei keine Rolle.

---

Resume Des rats de la race King-Holzman, mâles et femelles, de deux groupes d'âge (21 à 30 et 90 à 100 jours) ont été exposes à deux intensités accoustiques (30 et 90 db) et à 3 champs électriques (0, 1.600 et 16. 000 v/m). On a alors examiné leur capacité d'apprendre à nager dans un labyrinthe droite-gauche de Lashley modifié. Les critères d'examen furent le temps et le nombre de fautes commises pour sortir de l'eau. Les observations furent ensuite traitées par l'analyse de variances en tenant compte de répétitions (2 × 3 × 2 × 2 × 10). Les résultats montrent: (a) Les rats adultes préalablement exposés à des champs électriques on fait moins fautes que de jeunes individus et cela de façon significative quels que soient le sexe ou les conditions de bruit; (b) après avoir été exposés à des champs électriques, tous les rats ont nagé plus vite que les bêtes de contrôle; (c) après exposition au bruit, les femelles ont présenté des temps de sortie significativement plus élevés que les mâles pris dans des conditions identiques et cela quel qu'en soit l'âge et (d) après exposition simultanée au bruit et aux champs électriques, les mâles se sont trouvés moins habiles que les femelles, sans incidence de l'âge.

     

Genetic and radiation hybrid mapping of the hyperekplexia region on chromosome 5q.

Hyperekplexia, or startle disease (STHE), is an autosomal dominant neurologic disorder characterized by muscular rigidity of central nervous system origin, particularly in the neonatal period, and by an exaggerated startle response to sudden, unexpected acoustic or tactile stimuli. STHE responds dramatically to the benzodiazepine drug clonazepam, which acts at gamma-aminobutyric acid type A (GABA-A) receptors. The STHE locus (STHE) was recently assigned to chromosome 5q, on the basis of tight linkage to the colony-stimulating factor 1-receptor (CSF1-R) locus in a single large family. We performed linkage analysis in the original and three additional STHE pedigrees with eight chromosome 5q microsatellite markers and placed several of the most closely linked markers on an existing radiation hybrid (RH) map of the region. The results provide strong evidence for genetic locus homogeneity and assign STHE to a 5.9-cM interval defined by CSF1-R and D5S379, which are separated by an RH map distance of 74 centirays (roughly 2.2-3.7 Mb). Two polymorphic markers (D5S119 and D5S209) lie within this region, but they could not be ordered with respect to STHE. RH mapping eliminated the candidate genes GABRA1 and GABRG2, which encode GABA-A receptor components, by showing that they are telomeric to the target region.     

Site-directed mutagenesis of the CP 47 protein of photosystem II: 167W in the lumenally exposed loop C is required for photosystem II assembly and stability

The intrinsic chlorophyll-protein CP 47 is a component of photosystem II which functions in both light-harvesting and oxygen evolution. Using site-directed mutagenesis we have produced the mutant W167S which lies in loop C of CP 47. This strain exhibited a 75% loss in oxygen evolution activity and grew extremely slowly in the absence of glucose. Examination of normalized oxygen evolution traces indicated that the mutant was susceptible to photoinactivation. Analysis of the variable fluorescence yield indicated that the mutant accumulated very few functional PS II reaction centers. This was confirmed by immunoblotting experiments. Interestingly, when W167S was grown in the presence of 20 M DCMU, the mutant continued to exhibit these defects. These results indicate that tryptophan 167 in loop C of CP 47 is important for the assembly and stability of the PS II reaction center.