Silver ions inhibit the ethylene-stimulated production of ripening-related mRNAs in tomato

Abstract. Silver ions effectively inhibited both the initiation and the continuation of tomato ( Lyeopersicon esculentum Mill) ripening. Studies of protein synthesis in vivo showed that application of 2 mol m⁻³ silver thiosulphate to mature green fruit prevented the appearance of several novel proteins associated with ripening, including the softening enzyme polygalacturonase. However, total protein synthesis, as judged by the incorporation of [³⁵S] methionine into proteins, continued unabated after silver treatment. Ripening was also arrested when silver was supplied after ripening had begun. The accumulation of several ripening-related mRNAs, including that for polygalacturonase, was studied by translation in vitro and using cDNA clones as hybridization probes. Silver was shown to prevent the appearance of polygalaturonase mRNA when supplied to mature green fruit and to cause a rapid reduction in the concentration of mRNA for polygalacturonase and other ripening-related proteins when supplied after ripening had begun. It is proposed that silver exerts its effects due to interaction with the ethylene perception mechanism. The results suggest that perception of ethylene is vital not only for the initiation of ripening but also for the continued expression of genes required for ripening.     

Diet segregation between two colonies of little penguins Eudyptula minor in southeast Australia

We studied foraging segregation between two different sized colonies of little penguins Eudyptula minor with overlapping foraging areas in pre‐laying and incubation. We used stomach contents and stable isotope measurements of nitrogen (δ¹⁵N) and carbon (δ¹³C) in blood to examine differences in trophic position, prey‐size and nutritional values between the two colonies. Diet of little penguins at St Kilda (small colony) relied heavily on anchovy while at Phillip Island (large colony), the diet was more diverse and anchovies were larger than those consumed by St Kilda penguins. Higher δ¹⁵N values at St Kilda, differences in δ¹³C values and the prey composition provided further evidence of diet segregation between colonies. Penguins from each colony took anchovies from different cohorts and probably different stocks, although these sites are only 70 km apart. Differences in diet were not reflected in protein levels in the blood of penguins, suggesting that variation in prey between colonies was not related to differences in nutritional value of the diet. Anchovy is currently the only available prey to penguins throughout the year and its absence could have a negative impact on penguin food supply, particularly at St Kilda where the diet is dominated by this species. While it is difficult to establish whether diet segregation is caused by inter‐ or intra‐colony competition or spatial differences in foraging areas, we have shown that colonies with broadly overlapping foraging ranges could have significant differences in trophic position, diet composition and prey size while maintaining a diet of similar nutritional value.     

COLI-AEROGENES BACTERIA FROM FARM DAIRY EQUIPMENT AND RAW MILK

SUMMARY: A series of 1,040 cultures of coli-aerogenes bacteria isolated at 30° from farm dairy equipment and raw milk was classified according to the recommendations of the Coliform Sub-Committee of the Society for Applied Bacteriology (Report, 1949). The distribution of species and types isolated from milk did not differ materially from that for dairy equipment, Klebsiella cloacae, K. aerogenes and Citrobacter freundii being the dominant species, while the incidence of Escherichia coli was relatively low. There was no marked seasonal incidence of any type, though E. coli I formed a slightly higher proportion of the coli-aerogenes microflora in winter, whereas K. aerogenes I was slightly higher in summer. Many of the cultures of the dominant types, K. cloacae, K. aerogenes I and Cit. freundii I, did not form acid and gas from lactose in two days at 37°. Consequently 37° negative, anaerogenic and paracolon strains constituted a relatively high proporton (49%) of the coli-aerogenes microflora.     

The Ripening of Tomato Fruit as Affected by the Injection of Certain Chemicals

Some chemical agents known to uncouple oxidation from phosphorylationin biological systems were injected into mature green tomatofruit. Limited amounts of the substances accelerated the ripeningof fruit left on the plants but had no effect on picked fruit.L-Methionine, regarded as having a coupling action on oxidativephosphorylation, appeared to lengthen the ripening period. Aswell as speeding up ripening, DNP and CPA were also shown toincrease the activity of polygalacturonase, but not pectinesterase,in unpicked tomato fruit. It is concluded that even when subjectto the action of uncoupling substances, production of enzymesprobably necessary for the furtherance of the ripening processcontinues. The methods by which this process in tomato fruitcould be maintained are examined, and the possibility is discussedthat ‘loose’ coupling is the mechanism by whichan energy source is provided for the endergonic cell processestaking place during ripening.     

Satellite inventory of human settlements using nocturnal radiation emissions: a contribution for the global toolchest

Time series data from the Defense Meteorological Satellite Program (DMSP) Operational Linescan System (OLS) have been used to derive georeferenced inventories of human settlements for Europe, North and South America, and Asia. The visible band of the OLS is intensified at night, permitting detection of nocturnal visible-near infrared emissions from cities, towns, and villages. The time series analysis makes it possible to eliminate ephemeral VNIR emission sources such as fire and to normalize for differences in the number of cloud-free observations. An examination of the area lit (km²) for 52 countries indicates the OLS derived products may be used to perform the spatial apportionment of population and energy related greenhouse gas emissions.