Genetic identification and reiterated captures suggest that the Astyanax mexicanus El Pachón cavefish population is closed and declining

The sizes of Astyanax mexicanus blind cavefish populations of North-East Mexico are demographic parameters of great importance for investigating a variety of ecological,evolutionary,and conservation issues.However,few estimates have been obtained.For these mobile animals living in an environment difficult to explore as a whole,methods based on capture-mark-recapture are appropriate,but their feasibility and interpretation of results depend on several assumptions that must be carefully examined.Here,we provide evidence that minimally invasive genetic identification from captures at different time intervals(three days and three years)can give insights into cavefish population size dynamics as well as other important demographic parameters of interest.We also provide tools to calibrate sampling and genotyping efforts necessary to reach a given level of precision.Our results suggest that the El Pachón cave population is currently very small,of an order of magnitude of a few hundreds of individuals,and is distributed in a relatively isolated area.The probable decline in population size in the El Pachón cave since the last census in 1971 raises serious conservation issues.

Genetic Identification of a New Small Grain Dwarf Gene in Rice

The plant material used in the study was rice line 162d, a new small grain dwarf mutant. Polymorphic analysis of 221 SSR loci demonstrated that 162d derived from a semidwarf variety Shuhui 162 through mutation, and 162d and Shuhui 162 were just a pair of near isogenic lines. Genetic analysis of F_1 and F_2 populations suggested that dwarfism in 162d was controlled by a single recessive gene. Phenotypic characteristics of the mutant gene were that plant height was about a quarter of normal height, grain size about a quarter of normal size, leaf was short and broad, and seed setting rate was very low, compared with the near isogenic line Shuhui 162. The mutant gene was sensitive to gibberellin (GA_3) treatment and did not located on the region near the centromere of rice chromosome 5, where dl gene located. Therefore, it was concluded that the mutant gene of 162d was a new small grain dwarf gene in rice.

Application of Genetic Algorithms in Identification ofLinear Time-Varying System

By applying genetic algorithms (GA) to on-line identification of linear time-varying systems; a number of modifications are made to the Simple Genetic Algorithm to improve the performance of the algorithm in identification applications. The simulation results indicate that the method is not only capable of following the changing parameters of the system, but also has improved the identification accuracy compared with that using the least square method.

Genetic Variation of Porcine Circovirus Type 2 Isolate 201105ZJ

[Objective] This study aimed to investigate the genetic variation of porcine circovirus type 2 （PCV2） in China. [Method] The strain was isolated from infected samples by cel passage and preliminarily identified by PCR and IFA. Ful-length genome of the isolated strain was obtained by specific amplification for homology and phylogenetic analysis. [Result] A PCV2 strain was successful y isolated and named 201105ZJ, which could proliferate in PK15 cel lines. Specific fragments could be amplified by specific PCR assay. According to results of IFA assay, specif-ic immunofluorescence was observed; the TCID50 was low （102.67）; the ful-length genome sequence of the isolated strain was 1 768 bp, sharing 94.1%-96.8% ho-mology with 13 reference strains; to be specific, the isolated strain exhibited the highest homology of 96.8% with AF055392PCV2a; the isolated strain 201105ZJ and reference strain AF055392 belonged to genotype PCV2a, exhibiting a distant genetic relationship with genotype PCV2c. [Conclusion] Characteristics of genetic variation of PCV2 isolate 201105ZJ provided theoretical basis for vaccine development, investi-gation of PCV2 pathogenesis, and prevention and control of porcine circovirus-as-sociated diseases （PCVAD） in East China.