ABSTRACT
Symptoms of sugarcane orange rust were observed on July 17, 2008 on sugarcane cvs. Mex 57-1285, Mex 61-230, and Co 301 (a clone received in Mexico in 1953) at the Centro de Investigación y Desarrollo de la Caña de Azúcar en Tuxtla Chico, Chiapas, Mexico. In El Salvador, from August 2008 through January 2009, rust symptoms were observed on cv. CP 72-2086 (previously resistant to brown rust caused by Puccinia melanocephala Syd. & P. Syd.) in 117 dispersed sugarcane-production fields in various localities of El Salvador. Likewise, rust symptoms were first observed on sugarcane cv. SP 74-8355 (more than 25% severity and considered resistant to brown rust) at Natá, Coclé Province in Panama from January to February 2008. Dried herbarium leaf samples of sugarcane rust-infected leaves collected in El Salvador and Mexico were sent to the ARS, USDA Systematic Mycology and Microbiology Laboratory in Beltsville MD for identification. Panamanian samples were collected similarly and analyzed at the CALESA Biotechnology Laboratory. Morphological features of uredinial lesions and urediniospores were distinct from those of P. melanocephala and consistent with P. kuehnii E. J. Butler observed previously on specimens from Florida, Guatemala, Costa Rica, and Nicaragua (1-3). Analysis of the ITS1, 5.8S, and ITS2 and 28S large subunit rDNA sequences of the rust on infected cvs. Mex 57-1285, Mex 61-230, and Co 301 (BPI 878930, 879139, and 879140; GenBank Accession Nos. GO283006, GO283004, and GO283005, respectively) from Mexico and cv. CP 72-2086 from three locations in El Salvador (BPI 879135, 879136, and 879137; GenBank Accession Nos. GO283009, GO283007, and GO283008, respectively) all confirmed the identification of P. kuehnii. Similar analysis of the ITS1, 5.8S, and ITS2 rDNA sequence for the rust infecting cv. SP 74-8355 (GenBank Accession No. GO281584) confirmed the identification of P. kuehnii in Panama. To our knowledge, this is the first report of P. kuehnii causing orange rust disease of sugarcane in El Salvador, Mexico, and Panama. These findings also confirm the wider distribution of orange rust in the Western Hemisphere. References: (1) E. Chavarria et al. Plant Dis. 93:425, 2009. (2) J. C. Comstock et al. Plant Dis. 92:175, 2008. (3) W. Ovalle et al. Plant Dis. 92:973, 2008.
ABSTRACT
The aim of this paper was to analyze the renal performance of the insectivorous desert mouse opossum, Thylamys pusilla, a marsupial that inhabits temperate drylands of the Neotropics. We measured the urine concentrating ability of this marsupial in the field and under three different experimental conditions in the laboratory. (1) Ad libitum treatment: animals were fed ad lib. on apples, sausages and cat food; (2) restriction treatment: foods high in nitrogen were supplied ad lib., while only apple, a food with high water to nitrogen load, was restricted, and (3) fasting: 2 days of food deprivation. Osmolarity values recorded in the field were similar to those obtained under the restriction treatment. The maximum urinary concentration found (9015 mOsm/l) is the highest reported for a marsupial and more in keeping with similarly sized desert rodents. Similar urine concentrations in T. pusilla and desert rodents suggest that xeric environments, rather than phylogeny, play a major role in water conservation. The kidney of T. pusilla possesses a long papilla and shows high renal indices (M/C: 9.37; RMT: 11.76). Our results question the idea that urine concentration is not high in desert-dwelling insectivores. Although their dietary water intake is potentially high, this may not always be sufficient to eliminate the nitrogenous waste resulting from insectivory. Thus, T. pusilla uses its ability to conserve water to overcome periods of food shortage and high nitrogen load.
