Specific Inhibition of the Cyanide-insensitive Respiratory Pathway in Plant Mitochondria by Hydroxamic Acids

Hydroxamic acids, R-CONHOH, are inhibitors specific to the respiratory pathway through the alternate, cyanide-insensitive terminal oxidase of plant mitochondria. The nature of the R group in these compounds affects the concentration at which the hydroxamic acids are effective, but it appears that all hydroxamic acids inhibit if high enough concentrations are used. The benzhydroxamic acids are effective at relatively low concentrations; of these, the most effective are m-chlorobenzhydroxamic acid and m-iodobenzhydroxamic acid. The concentrations required for half-maximal inhibition of the alternate oxidase pathway in mung bean (Phaseolus aureus) mitochondria are 0.03 mm for m-chlorobenzhydroxamic acid and 0.02 mm for m-iodobenzhydroxamic acid. With skunk cabbage (Symplocarpus foetidus) mitochondria, the required concentrations are 0.16 for m-chlorobenzhydroxamic acid and 0.05 for m-iodobenzhydroxamic acid. At concentrations which inhibit completely the alternate oxidase pathway, these two compounds have no discernible effect on either the respiratory pathway through cytochrome oxidase, or on the energy coupling reactions of these mitochondria. These inhibitors make it possible to isolate the two respiratory pathways and study their mode of action separately. These inhibitors also enhance an electron paramagnetic resonance signal near g = 2 in anaerobic, submitochondrial particles from skunk cabbage, which appears to be specific to the alternate oxidase and thus provides a means for its assay.     

Proteins of the sieve-tube exudate of Cucurbita maxima

Summary Sieve-tube exudate which appears on cut surfaces of stems of Cucurbita maxima as distinct droplets has been depicted in electron micrographs of longitudinal sections of the phloem. The exudate, which was produced from mature sieve tubes only, contained filaments of P-protein, but no mitochondria or vesicles of endoplasmic reticulum. The water-soluble part of the exudate contained at least 12 proteins, as shown by disc-electrophoresis. Enzymic activity was found for peroxidases, acid phosphatases, and aldolases. Color tests and assays for other enzymes, including ATPase, fructokinase, several dehydrogenases, and UDP-glucose: D-fructose-2-glucosyl transferase, gave negative results. With repeated cutting of a stem, the protein content of the exudate increased, while the amount of exudate decreased.Supported by Deutsche Forschungsgemeinschaft and Stiftung Volkswagenwerk. During part of this investigation the senior author held a U.S. National Science Foundation Senior Foreign Scientist Fellowship at the University of Wisconsin.     

Aspects of the ecology and energetics of the egg sac parasites of the wolf spider Pardosa lugubris (Walckenaer)

Summary The egg sacs of the wolf spider Pardosa lugubris are parasitised by two ichneumonid wasps, namely Gelis micrurus and Hidryta sordidus. The parasites are bivoltine, the first generation parasitising the summer egg sac of P. lugubris and the second generation parasitising, and overwintering in, the autumn egg sac. Parasitised egg sacs have a characteristic appearance.The degree of egg sac parasitism was 9.8% and 6.9% for the two egg sac batches in 1965 and 2.9% and 34.8% for those of 1966. The degree of parasitism varies from area to area as does the percentage parasitism attributable to the two species.The gross growth efficiency for Hidryta from the first egg sac is 31.2% and from the second 16.2%. 3.0% in 1965 and 4.3% in 1966, of the annual yield from P. lugubris to predators and parasites, goes to the egg sac parasites. This represents reductions in recruitment of 9.1% in 1965 and 10.9% in 1966.     

Leonhardi Euleri's “Principia pro motu sanguinis per arterias determinando”

The purpose of this publication as a pedagogical contribution is to illustrate the uniqueness of the method Euler used to determine the unsteady flow of blood in the circulatory system. In his presentation, he accounts for the tapering of the vessels and their elastic behavior. The limitations of this study are based upon the extent of the development of the mathematics of his era. This work may be the first mathematical treatment of circulatory physiology and haemodynamics. Euler perhaps could very well be called the Father of Haemodynamics.The Determination of the Principals of the Motion of Blood through the Arteries.Supported in part by a grant from the American Heart Association (No. 62F4EG).This work was done during the tenure of an Established Investigatorship of the American Heart Association.     

The course of the first meiotic prophase in Beta procumbens and in the F1 between B. vulgaris and B. procumbens

Summary The succession of the stages of the first meiotic prophase in Beta procumbens has been ascertained by measurements of the nuclear volume and by other criteria. By this method it has been possible to relate the appearance of pairing gaps to the beginning separation of the chromosomes after pachytene. A zygotene-like stage of early diplotene has been found. Asynchronous condensation of the bivalents and reduction of the chiasma frequency have been observed in diplotene and diakinesis. — The lengths and arm ratios of the pachytene chromosomes of Beta procumbens were determined.Stages similar to those in B. procumbens have been recognized in the F ₁ hybrid between Beta vulgaris and Beta procumbens. The pachytene chromosomes appeared to be paired to a great extent. However, only some of the cells showed bivalents in diakinesis, in the majority desynapsis occurred during diplotene or early diakinesis. In metaphase I, bivalents, univalents, cases of secondary association due to stickiness and cases of fragmentation have been observed.

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Zusammenfassung Die Stadienabfolge während der ersten meiotischen Prophase bei Beta procumbens wurde auf Grund verschiedener Kriterien, vor allem durch Messungen des Kernvolumens, bestimmt. Dadurch konnte das Auftreten von Paarungslücken auf die post-pachytänische Trennung der Chromosomen zurückgeführt werden. Während des frühen Diplotäns wurde ein Zygotän-ähnliches Stadium gefunden. Asynchrone Kondensation der Bivalente und Reduzierung der Chiasmenzahl wurden im Diplotän und in der Diakinese beobachtet. — Die Längen- und Armlängen-Verhältnisse der Pachytän-Chromosomen von Beta procumbens wurden bestimmt.Die gleichen Stadien wie bei Beta procumbens traten auch in der F ₁-Hybride zwischen B. vulgaris und B. procumbens auf. Die Pachytän-Chromosomen lagen offenbar weitgehend im gepaarten Zustand vor. Dennoch besaß in der Diakinese nur ein Teil der Zellen Bivalente, im größeren Teil der Zellen erfolgte während des Diplotäns oder der frühen Diakinese Desynapsis. In der Metaphase I wurden Bivalente, Univalente, Fälle von sekundärer Assoziierung (infolge stickiness) sowie Fälle von Chromosomen-Fragmentierung beobachtet.

     

Zur Frage der Verteilung des Rh(D)-Faktors bei erstgeborenen und nachgeborenen Kindern

Summary The frequency of the occurrence of the Rh(D)-factor was compared in 1185 first-born babies with that among 2246 children from 2nd and later pregnancies. Among the first-born children 14,2% were Rh(D)-negative, and among the later-born 14,7% were Rh(D)-negative. In children with the Blood group O the distribution of the Rh(D) bloodgroup was the same in both first-born and later-born children. Among the Rh(D)-positive children there seem to be less boys.     

Über den unterschiedlichen Formwechsel des Heterochromatins in der mitotischen Prophase vonLithospermum undLilium

Zusammenfassung In den Zellkernen vonLithospermum purpurocaeruleum setzt die mitotische Prophase so wie bei anderen Arten unter Zerstäubung der Chromozentren ein; an ihre Stelle treten Heterochromomeren, die sich im Höhepunkt an die umgebenden Euchromomeren angleichen. Später, wenn die Spiralisation der Chromosomen beginnt, zeigt sich wieder ein deutlicher Unterschied zwischen Eu- und Heterochromatin. Er bleibt kontinuierlich bis in die späte Prophase erhalten; erst dann erreichen die euchromatischen Teile der Chromosomen den gleichen Kontraktionszustand wie die heterochromatischen.BeiLilium henryi verläuft die Prophase anders. Im Zerstäubungsstadium wird zwar ebenfalls eine Zerlegung der interphasischen Chromozentren herbeigeführt, doch bleiben im gesamten weiteren Verlauf der Prophase eu- und heterochromatische Chromosomenteile völlig aneinander angeglichen.Die statistische Verteilung der Volumina der interphasischen und prophasischen Kerne spricht für die Zugehörigkeit des Zerstäubungsstadiums zur Prophase und gegen die Auffassung, daß es einem Teil der S-Periode zuzurechnen ist.

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In the nuclei ofLithospermum purpurocaeruleum mitotic prophase starts with the dispersion of the chromocenters, just as it does in other species, too; in place of the chromocenters heterochromomers come forth, which assimilate to the surrounding euchromomers at culmination time. Later, when the chromosomes begin to spiralize, a distinct differentiation in euchromatin and heterochromatin is visible again. It is conserved until late prophase. Only then the euchromatic parts of the chromosomes attain the same degree of spiralisation as the heterochromatic ones.InLilium henryi prophase takes another course. There is a decomposition of the interphase chromocenters in the dispersion stage, too, but during further prophase the euchromatic and heterochromatic parts of the chromosomes contract in the same way and are not differentiated from each other.The statistical distribution of the volumes of interphasic and prophasic nuclei confirms the assumption, that the dispersion stage belongs to prophase, and not to the S-period of interphase.

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Herrn Prof. Dr.Lothar Geitler, in Verehrung und Dankbarkeit zum 70. Geburtstag gewidmet.