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1 HFA-134a was administered to AHA rats by snout-only inhalation for 1 h daily to assess the effects of treatment on reproduction and development.2 In a fertility study, rats were exposed to atmospheres of 2500, 10000 or 50000 p.p.m. HFA-134a throughout gametogenesis, mating, pregnancy and lactation.3 In a peri- and post-natal study, rats were exposed to HFA-134a from days 17 to 20 of pregnancy and days 1 to 21 post partumto atmospheres of 1800, 9900 or 64 400 p.p.m.4 The only treatment-related effect was a slight reduc tion in body weight gain of males of the treated parental generation at 50 000 p.p.m. (fertility study).5 In neither study were there any adverse effects of HFA- 134a on the reproductive performance of treated animals or on the development, maturation or reproductive performance of up to two successive generations.

Observations and experimental data that were obtained from plants infected with bymoviruses such as barley yellow mosaic virus (BaYMV), barley mild mosaic virus (BaMMV), or wheat spindle streak mosaic virus (WSSMV) suggested that long-distance transport follows the phloem pathway. Inoculation of barley roots with BaMMV via viruliferous zoospores of Polymyxa graminis and mechanical inoculation of leaves revealed that viral transport from shoots to roots occurs in less than 5 d while movement from roots to shoots could only be detected after 5-6 weeks. A model for long-distance transport of bymoviruses was developed which shows that the bymovirus infection cycle passes through 4 main stages. During these stages an up- and downward movement may be important for sufficient replication and successful transmission of bymoviruses. The 28 kDa protein of BaYMV (RNA2) may have a function in either movement or replication as it was often found associated with virus particles. The other RNA2-encoded protein of BaYMV, a 70 kDa protein, could be involved in fungal transmission. ?tude de la migration des bymovirus et fonctions possibles des prot?ines de transport cod?es par l'ARN2 du virus de la mosa?que jaune de l'orge. Les diverses observations r?alis?es et les donn?es exp?rimentales obtenues ? partir de plantes infect?es par les bymoviruses, tel que le virus de la mosa?que jaune de l'orge (BaYMV), le virus de la mosa?que mod?r?e de l'orge (BaMMV) ou le virus de la mosa?que stri?e en fuseaux du bl? (WSSMV) sugg?rent que leur transport ? longue distance utilise les vaisseaux du phlo?me. L'inoculation des racines d'orge par le BaMMV, avec des zoospores de Polymyxa graminis contamin?s par le virus, et l'inoculation m?canique de feuilles r?v?lent que le transport du virus des feuilles aux racines s'effectue en moins de 5 j, tandis que le mouvement inverse est d?tect? 5 ? 6 sem apr?s l'infection. Nous avons d?velopp? un mod?le d'?tude du transport ? longue distance du bymovirus montrant que le cycle infectieux comprend 4 ?tapes principales. Le transport ascendant ou descendant des bymovirus pourrait jouer un r?le important pour leur r?plication et leur transmission. La prot?ine de 28 kDa du BaYMV (ARN2) pourrait intervenir dans le transport ou la r?plication du virus, car elle est souvent trouv?e associ?e aux particules virales. L'ARN2 codant pour une seconde prot?ine de BaYMV de 70 kDa pourrait participer ? la capacit? vectrice du champignon virulif?re.

Human glucose 6-phosphate dehydrogenase (G6PD) has a particularly large number of variants resulting from point mutations; some 60 mutations have been sequenced to date. Many variants, some polymorphic, are associated with enzyme deficiency. Certain variants have severe clinical manifestations; for such variants, the mutant enzyme almost always displays a reduced thermal stability. A homology model of human G6PD has been built, based on the three-dimensional structure of the enzyme from Leuconostoc mesenteroides. The model has suggested structural reasons for the diminished enzyme stability and hence for deficiency. It has shown that a cluster of mutations in exon 10, resulting in severe clinical symptoms, occurs at or near the dimer interface of the enzyme, that the eight-residue deletion in the variant Nara is at a surface loop, and that the two mutations in the A- variant are close together in the three-dimensional structure.