Birdsong Overlapping: Random Coincidence or Acoustic Interactions.

Birdsong overlapping may either indicate communicative interaction between birds or be a simple coincidence. We developed a program that allowed us to mathematically modulate the independent singing of birds with a given level of song rate. This permitted us to statistically evaluate whether song overlapping is a random coincidence or real acoustic interactions between birds. Analysis of automatic recording (Song Meter SM4) of singing detected the cases of reliable acoustic interactions between both conspecific and heterospecific individuals. They account for 6% of the total singing time. The most numerous and actively singing chaffinches (in the case of singing of several individuals) suppress the singing of other species. The singing of a single chaffinch, on the other hand, can provoke the singing of other species, involving previously silent neighbors in song duels. It is possible that it is the acoustic interactions that are responsible for maintaining the structure of the population at the end of the breeding season.

Complete nucleotide sequence and molecular probing of potato virus S genome.

Complete genomes of three isolates of Potato virus S (PVS) were cloned and sequenced. The PVS ORF-1 was characterized for the first time. It encodes a putative replication protein (RPT) that shares the highest homology (about 52%) with that of Blueberry scorch virus (BlScV). ORF-1 motifs, characteristic for carlaviruses were found for methyltransferase (MTR), helicase (HEL) and RNA-dependent RNA polymerase (RdRp). The complete sequence of PVS genome enabled to develop an immunocapture RT-PCR probing of the PVS genome. Using this system, the sequence variability of 11 genome zones was examined for 34 PVS isolates including 15 PVS-CS variants that caused a systemic infection in Chenopodium quinoa. A broad variability between PVS isolates and diverse sequence variants was found. cDNA fragments covering the coat protein (CP) leader and CP-coding region (approx. 420 bp) were pooled for PVS-O and Chenopodium-systemic PVS isolates (PVS-CS) and corresponding cDNA libraries were screened for sequence variants. Both cDNA pools differred mainly in the 5'-end of the CP gene. Methionine at the position 17 in combination with serine at the position 34 were frequently associated with the CS character of PVS. In general, hydrophobic and polar amino acids were characteristic for the positions 17 and 34, respectively in PVS-CS isolates. Genome probing and evolutionary distances suggested that the PVS-CS isolates analyzed were close to the ordinary European isolates of ordinary strain of PVS (PVS-O) but distant to the original Andean strain of PVS (PVS-A).

[The prevalence, causes and specific features of voice disturbances in teachers]. / Rasprostranennost', prichiny i osobennosti narushenii golosa u pedagogov.

The paper analyzes voice disturbances, their causes and specific features in teachers based on the questionnaires filled by 934 general educational school teachers. The teachers have been found to associate voice disturbances not only with changes in the voice timbre, but with different subjective feelings that make their professional activity difficult. The major factors that cause voice disturbances are the voice overloads that differ in teachers of different specialities, their inability to use the voice, psychoemotional stresses, and frequent colds, as well as a combination of several factors. The incidence of vocal apparatus diseases does not tend to decrease, which makes it necessary to implement combined medical and pedagogical prophylactic measures to prevent dysphonia.