Discrimination Amongst Leishmania by Polymerase Chain Reaction and Hybridization with Small Subunit Ribosomal DNA Derived Oligonucleotides

ABSTRACT. A method for discriminating among Leishmania is described, based upon small subunit ribosomal DNA sequence differences. The method was to amplify the entire 2.2 kb small subunit rDNA by polymerase chain reaction using conserved primers specific for the 5' and 3' termini of the small subunit ribosomal RNA, and then hybridize the product dotted onto nylon membranes with labeled oligonucleotides. The design of the hybridization probes was based upon complete small subunit rDNA sequences from L. amazonensis, L. major and L. guyanensis and partial sequences of L. mexicana, L. braziliensis, L. tropica and L. chagasi. A high degree of sequence similarity (> 99%) among species was found. However, sufficient sequence divergence occurred to permit the design of internal oligonucleotide probes specific for species complexes. This procedure successfully discriminated amongst a wide range of Leishmania isolates. The method detected as few as 10 cultured organisms and detected parasites in tissue samples from experimentally infected animals. Non-radioactive labeling showed the same specificity and sensitivity as radioactive probes.     

Induction of l-Serine Dehydratase in Aeromonas punctata

l -Serine dehydratase (SD) was produced to the extent of only 0·04 international unit (iu) per mg dry weight by Aeromonos punctata NRRL B-928 when grown on a chemically defined medium. Addition of 2% (w/v) l -serine to this medium increased SD ten-fold or more, indicating a significant inductive effect. d -Serine was toxic to the organism, making weights and enzyme titres uncertain, but dl -serine induced a specific activity of SD at least equal to that from the l enantiomorph. With complex media containing beef extract, the toxic effect of d -serine was partially overcome, and sufficient growth was obtained to permit reliable analytical figures; d -serine induced slightly better specific activities than the l isomer. dl -Serine at 2% concentration induced a specific activity of 1·2 iu/mg, twice that of l -serine at that level.     

Animal behavior can inform conservation policy,we just need to get on with the jobor can it？

1 Conservation Behavior as an Emerging Discipline on the Brink of Success, or Unrealistic Ideal？
It seems intuitively sensible that an understanding of the behavioral characteristics of animals, such as their home ranges, diets, mating systems, and dispersal me- chanisms, may be useful to inform conservation efforts in determining, for example, suitable reintroduction areas, or the design of dispersal corridors.     

THE COMMUNICATIVE SIGNIFICANCE OF TONALITY IN BIRDSONG: RESPONSES TO SONGS PRODUCED IN HELIUM

ABSTRACT

“Pure tones” are a distinctive acoustic feature of many birdsongs. Recent research on songbird vocal physiology suggests that such tonal sounds result from a coordinated interaction between the syrinx and a vocal filter, as demonstrated by the emergence of harmonic overtones when a bird sings in helium. To investigate the communicative significance of vocal tract filtration in the production of birdsong, we used field playback experiments to compare the responses of male swamp sparrows Melospiza georgiana to normal songs and those same songs recorded in helium. We also measured responses to pure tone songs that had been shifted upward in frequency to match the average spectra of those songs with added harmonics. Male sparrows were significantly more responsive to the playback of normal songs than to either helium songs with added harmonics or frequency- shifted pure tone songs. Songs with harmonics retained a high degree of salience, however. We conclude that explanations for the occurrence of tonal sounds in birdsongs must consider perceptual attributes of songs as communicative signals, as well as problems of song production and transmission.