Syrian pear (Pyrus syriaca) as a pollinator for European pear (Pyrus communis) cultivars

In Israel four European pear cultivars are grown: ‘Spadona’ is the main cultivar and ‘Coscia’, ‘Gentile’ and ‘Spadochina’ are its pollinators. However, molecular S-genotyping revealed that ‘Spadona’ is semi-compatible with its three pollinators. This explains, at least in part, the relatively low pear yield in Israel. The Syrian pear (Pyrus syriaca) grows wild in Israel and blooms intensively, overlapping the blooming of the cultivated European pears. Cross-fertilization between Syrian pear and ‘Spadona’ was shown to be efficient suggesting that Syrian pear might be a potent pollinator for ‘Spadona’. Twenty-six Syrian pear seedlings, from different sites in north-east Israel were S-genotyped identifying 11 that are fully compatible with the four European pear varieties cultivated in Israel. By this screening, 24 different S-RNases were cloned; ten of them are new, whereas the other fourteen had been identified previously. In addition, seedlings of two wild pear species were also S-genotyped. Two seedlings from Pyrus betulifolia and one from Pyrus korshinskii were found to be genetically compatible with the four European pear cultivars. From these seedlings four S-RNases were cloned, two are new, one had been cloned previously and one was identical to an S-RNase allele cloned from Syrian pear in this work.     

Identification of seven haplotype-specific SFBs in European pear (Pyrus communis) and their use as molecular markers

The European pear (Pyrus communis) carries the S-RNase-mediated gametophytic self-incompatibility (GSI) system. The S-haplotype is conferred by an S-locus, which contains the style-specific expressed S-RNase, and the pollen-specific expressed F-box genes (SFB). Both the S-RNase and the SFB genes are multi-allelic and each is characteristic of one of the S-haplotypes. Therefore, they are ideal markers for molecular S-genotyping. In this work, for the first time, seven haplotype-specific SFBs were isolated from European pears. Particular primers for each of these SFBs were generated, thus providing an additional tool for S-genotyping of European pear cultivars.     

A study of experimental acute lung injury in pigs on zero end-expiratory pressure

OBJECTIVES: Tidal expiratory flow limitation (EFL) has been reported in humans with acute lung injury (ALI) and assumed to be associated with small airway closure. Detection of EFL is important because by selecting positive end-expiratory pressure at such a level that EFL is no longer present in the tidal breath, the repeated opening and closure of small airways can be prevented. The objective of this study was to investigate the occurrence of EFL in two experimental models of ALI. ANIMALS: Ten female piglets. METHODS: Animals were anaesthetized, tracheotomized and mechanically ventilated on zero end-expiratory pressure. Acute lung injury was induced by oleic acid (OA) (n = 5) or saline lavage (SL) (n = 5). Tidal EFL was assessed by the negative expiratory pressure test. Lung and chest wall mechanics were partitioned using an oesophageal balloon. Resistance and static elastance were assessed by a rapid airway occlusion technique at baseline ventilatory settings. RESULTS: There was no EFL at any time before and after ALI in both models. This may be due to an increased elastance which promoted higher expiratory flow after ALI and to a decreased chest wall to lung static elastance ratio which could favour small airways patency. The similar increase in total lung resistance, in the two models, after ALI was mostly due to an increased airway resistance in the OA model and to the lung tissue resistance in the SL model. CONCLUSIONS AND CLINICAL RELEVANCE: Tidal EFL was not detected in experimental ALI. This finding casts some doubt about the usefulness of some experimental models of ALI to mimic some reported findings in human ALI.