No abstract

No abstract

Accumulation of protochlorophyllide (Pchlide) was determined after incubation of etiolated seedlings of garden cress (Lcpidium sativum L.) with exogenous 5-aminolevulinate for 24 h. Young seedlings (start of incubation 0-12 h after imbibition) accumulated only moderate amounts (<0.2 nmol per seedling) of Pchlide. Maximum capacity of Pchlide accumulation (ca. 14 nmol per seedling) was reached at 30-36 h after imbibition. At 60-72 h after imbibition, the capacity of Pchlide formation from exogenous ALA was only 0.2-0.3 nmol per seedling. Uptake of ALA via roots was high in young and old seedlings. The carotenoid content and pattern did not change by ALA incubation. Precursors of Pchlide were also accumulated by ALA treatment. Predominant products were protoporphyrin and magnesium protoporphyrin (MgP) in 30 h old seedlings but magnesium protoporphyrin monomethylester (MgPMe) in 72 h old seedlings. The previously described interaction of Pchlide precursors with cab gene expression cannot be correlated with a single porphyrin. A possible correlation with the ratio MgPMe: MgP is discussed.

There is an association between the size of the cumulus investment and the in vitro developmental ability of the oocyte-cumulus complex (OCC) that provides a basis for the selection of OCCs. However, the value of selection is confounded by humoral interactions between OCCs that influence the development of OCCs of other grade(s). This study examined the effect of size of the cumulus investment (OCC grade) and the interactions between grades on the developmental ability of oocytes collected from the cow, ewe and lamb. OCCs were classified into A, B and C grades on visual assessment of the number of cumulus cell layers or left unselected (Unselected). In the cow, there were 669 +/- 228 to 4763 +/- 228 cells per OCC whereas comparable figures in the ewe and lamb were 593 +/- 252 to 3716 +/- 252 and 366 +/- 228 to 3263 +/- 228 respectively (A > Unselected > B > C; Experiment 1). In Experiment 2, OCCs were made to mature within grade and the efficiency of blastocyst production and blastocyst quality was compared with that obtained in the Unselected group. Grade was associated with significant (p < 0.05) differences in cleavage rate, blastocyst production rate and the mean number of nuclei per embryo (generally A > B > C across animal types). However, the performance of A grade OCCs in the cow and lamb did not differ significantly from that obtained in the Unselected group whereas in the ewe, A grade OCCs were significantly (p < 0.05) better. Furthermore, the performance of the Unselected group was significantly (p < 0.05) better than that of the combined grades (A + B + C) in the cow but there were no differences in either the ewe or lamb. It is concluded that (i) interactions between OCCs of different grade influence the developmental ability of OCCs in the cow and, to a lesser extent, the lamb, (ii) selection of OCCs in the cow and lamb would lead to the exclusion of many OCCs that have the ability to develop into blastocysts and (iii) selection in the ewe would improve the efficiency of blastocyst production although its value is limited by the low percentage of A grade OCCs.

(Perfluoroalkyl)(dimethylamino)sulfonfum Hexafluoroarsenates MeN = S(CF3)2 (5) is alkylated by Me30@ AsFg to Me,N-S(CF3)-f' AsFg (4). From 5 and MeOSO@ AsFg (6) MeOS(0)-N(Me)S(CF3)y AsFg (7) is formed as a relatively stable primary product. Decomposition of 7 gives the expected 4 only in poor yield. Nucleophilic substitution of the sulfur-bonded fluorine in CF,SFF AsFg (8) by Me3SiNMe2 yields CF3S(NMe2)p AsFP (9). Similarly, (CF3),CFSF9 AsFP (10) reacts with dimethyl(trimethylsily1)amine to give (CF&CFS(NMe2)9 AsFg (11). The structures of 4 and 9 are elucidated by X-ray analyses, and the influence of the substituents on the bonding is discussed.Sulfoniumsalze besitzen eine groBe Bedeutung in der organischen Synthese als Zwischenprodukte'). Uber ihre Strukturen und die Bindungsverhaltnisse in den Kationen ist jedoch relativ wenig bekannt. Von anorganischer Seite sind in den letzten Jahren eine Reihe von Untersuchungen durchgefuhrt worden2); Strukturbestimmungen der Halosulfonium-Kationen SFF 3)r CF3SF? 4), Me,NSFp 4), SClF ' I, CF3SClp 6a), CH3SCl,$ 6b) und SBrp ' I, haben gezeigt, da8 die Strukturen dieser Kationen denen der isoelektronischen Phosphane entsprechen. Ziel unserer Untersuchungen ist es, allgemeine Synthesewege zu Sulfonium-Ionen zu entwickeln und die Chemie dieser Kationen mit der der isoelektronischen Phosphane zu vergleichen. Strukturuntersuchungen sollen zeigen, wie weit wechselseitige Ruckschlusse bzw. Vorhersagen zwischen diesen beiden isoelektronischen Systemen gemacht werden konnen. Zu diesem Zweck variieren wir in den Sulfonium-Salzen R1R2R3S@ systematisch die Substituenten R', R2, R3 = F, CF3, NMe2 und NCO. In der vorliegenden Arbeit berichten wir uber die Darstellung und die Strukturen von Me2NS(CF3)p AsFF (4) und (Me2N)*SCF? AsF? (9) sowie uber die Synthesen von (CF3)2CFSFp AsF? (10) und (CF3)2CFS(NMe2p AsFP (11). 6+ 8+ Ergebnisse und Diskussion A. Praparative UntersuchungenFur die Synthese von Sulfonium-Ionen bieten sich die folgenden Wege an:1. Halogenid-Ionen-Abstraktion aus pseudo-pentakoordinierten Sulfuranen mit Halogen-Lewi~-Sauren~.~**) gemaB R~R~S + x@ YQ --+ R'R~SXQ YQ (2) 3. Alkylierung von A = S-Mehrfachbindungen'2):4. Nucleophile Substitution an Halogensulfoniumsalzen, z. B. mit Silylaminen'3-1s):5. Zersetzung von Sulfuranoniumsahen'6):