Süßwasser-Algenarten in Einzeldarstellung VI.Spirogyra gaterslebensis,eine neue Art der Sektion Salamacis

Summary Spirogyra gaterslebensis nov. spec.Vegetative cells 18–21 × (88,5-) 109–182 (–223,5) µm, with replicate end walls. 1 Chromatophore, making (4-) 5–6 (–8) turns, rarely 2 Chromatophores with (1,5-) 2 (–3) turns. Conjugation lateral and scalariform; tubes formed ± by both gametangia; fertile cells abruptly inflated to 41,5–52,0 (–70,0) µm in diameter. Zygospores ellipsoid 26,0–34,0–45,0 (–52,0) × 41,5–47,0–78,0 (–96,0) µm; median spore wall yellow, finely punctate, on the poles sometimes with a few wrinkles.In the GDR in a road ditch between Gatersleben and Quedlinburg with shallow, slowly running water, together withVaucheria woroniniana Heering V. debaryana Woronin andV. sessilis (Vauch.) D.C. April–Mai 1967.

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. VI.Spirogyra gaterslebensis, Salamacis

Spirogyra gaterslebensis nov. spec. : , Vaucheria woroniniana Heering,V. debaryana Woronin V. sessilis (Vauch.) D. C. 25. IV — 16. V. 1967. . .

     

EinBatrachospermum der Sektion Contorta Skuja aus Kuba

Zusammenfassung Es wird über ein Vorkommen der bisher nur aus China bekannten Süßwasser-RotalgeBatrachospermum intortum Jao 1941 an mehreren Standorten im gebirgigen Osten (Provinz Oriente) der Insel Kuba berichtet. Es dürfte sich um den ersten Nachweis der Gattung für diese Antilleninsel handeln.

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ABatrachospermum, Sect. Contorta Skuja from Cuba

Summary Batrachospermum intortum hitherto known only from China, was found on several localities in the mountainous eastern part of Cuba (Prov. Oriente). This may be the first report of the genus for this island.

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Batrachospermum Contorta Skuja

Batrachospermum intortum Jao 1941, , . ( ). .

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Ergebnisse der 1. Kubanisch-deutschen Alexander von Humboldt-Expedition 1967/68, Nr. 33.     

Assessment of genetic diversity among African cassava Manihot esculenta Grantz accessions resistant to the cassava mosaic virus disease using SSR markers

A study was conducted to determine the extent of genetic diversity among African cassava (Manihot esculenta Crantz) accessions resistant to the cassava mosaic virus disease (CMD), using simple sequence repeat (SSR) markers. The accessions included a breeding stock (clone 58308), five improved lines, 62 CMD resistant and 10 CMD susceptible landraces. Genetic diversity was assessed among accessions in five cluster groups derived from UPGMA analysis on data from 18 SSR primer pairs. Average gene diversity, He, was high in all cluster groups, with an average heterozygosity of 0.591 ± 0.061. The estimator of inbreeding Fis revealed a low level of inbreeding within groups and averaged −0.262 ± 0.142. Gene diversity among all accessions was 51.4% and gene diversity within cluster groups was 46.6%, while 4.8% was due to diversity between the different cluster groups. The amount of genetic differentiation measured by Gst and Fst were 9.6% and 12.1% respectively, indicating a weak genetic structure.     

Über einige Spirogyren aus dem Harz

Zusammenfassung In Algenaufsammlungen aus dem Harzgebiet wurden achtSpirogyra-Arten gefunden, an Freiland- sowie Kulturmaterial untersucht und dabei die Variationsbreite einiger Merkmale durch umfangreiche Messungen geprüft.

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On someSpirogyra species of the Harz mountains

Summary Eight species ofSpirogyra found in collections of algae from the Harz mountains were studied on living material from the natural site and on cultures derived from it. Based on numerous measurements, the variability of some characteristics is investigated.

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8 Spirogyra. ; .

     

Charge transfer equilibria between diamond and an aqueous oxygen electrochemical redox couple

Undoped, high-quality diamond is, under almost all circumstances, one of the best insulators known. However, diamond covered with chemically bound hydrogen shows a pronounced conductivity when exposed to air. This conductivity arises from positive-charge carriers (holes) and is confined to a narrow near-surface region. Although several explanations have been proposed, none has received wide acceptance, and the mechanism remains controversial. Here, we report the interactions of hydrogen-terminated, macroscopic diamonds and diamond powders with aqueous solutions of controlled pH and oxygen concentration. We show that electrons transfer between the diamond and an electrochemical reduction/oxidation couple involving oxygen. This charge transfer is responsible for the surface conductivity and also influences contact angles and zeta potentials. The effect is not confined to diamond and may play a previously unrecognized role in other disparate systems.     

Software and the future of programming languages

Although software is the key enabler of the global information infrastructure, the amount and extent of software in use in the world today are not widely understood, nor are the programming languages and paradigms that have been used to create the software. The vast size of the embedded base of existing software and the increasing costs of software maintenance, poor security, and limited functionality are posing significant challenges for the software R&D community.