Sex differences in the electrocommunication signals of the electric fish Apteronotus bonapartii

The South American weakly-electric knifefish (Apteronotidae) produce highly diverse and readily quantifiable electrocommunication signals. The electric organ discharge frequency (EODf), and EOD modulations (chirps and gradual frequency rises (GFRs)), vary dramatically across sexes and species, presenting an ideal opportunity to examine the proximate and ultimate bases of sexually dimorphic behavior. We complemented previous studies on the sexual dimorphism of apteronotid communication signals by investigating electric signal features and their hormonal correlates in Apteronotus bonapartii, a species which exhibits strong sexual dimorphism in snout morphology. Electrocommunication signals were evoked and recorded using a playback paradigm, and were analyzed for signal features including EOD frequency and the structure of EOD modulations. To investigate the androgenic correlates of sexually dimorphic EOD signals, we measured plasma concentrations of testosterone and 11-ketotestosterone. A. bonapartii responded robustly to stimulus playbacks. EODf was sexually monomorphic, and males and females produced chirps with similar durations and amounts of frequency modulation. However, males were more likely than females to produce chirps with multiple frequency peaks. Sexual dimorphism in apteronotid electrocommunication signals appears to be highly evolutionarily labile. Extensive interspecific variation in the magnitude and direction of sex differences in EODf and in different aspects of chirp structure suggest that chirp signals may be an important locus of evolutionary change within the clade. The weakly-electric fish represent a rich source of data for understanding the selective pressures that shape, and the neuroendocrine mechanisms that underlie, diversity in the sexual dimorphism of behavior.     

肝素钠的生产及其存在的问题及解决的方法（Ⅱ）

本文就粗品肝素钠生产的原料控制硬件设施管理和环保等方面进行了论述，介绍了一些改进的方法和措施，并就该方面的的一些问题进行了探讨，提出了解决的方法。     

Effect of feeding fungal endophyte (Acremonium coenophialum )-infected tall fescue seed on reproductive performance in CD-1 mice through continuous breeding

This study was designed to assess the effect of endophyte-infected (Acremonium coenophialum ) tall fescue (KY-31) seed (80% infected) on reproductive performance in CD-1 mice by continuous breeding. Twenty-four pairs of 70-d-old CD-1 mice were randomly allocated to four diets: 1) mouse chow ad libitum; 2) 40% infected fescue seed and 60% chow (w/w); 3) reduced intake (100% chow) similar to the intake, adjusted daily, in Diet 2; and 4) 60% infected fescue seed and 40% chow. Males and females were randomly paired (six pairs/treatment) and placed on the above diets. The mice were fed the corresponding diets for 80 d, although the pairs were separated on Day 60 (prior to the birth of the 3rd litter) and the females were monitored for one additional gestation period (20 d). The pregnancy data (litters produced) among the four treatments were 100.0 (18), 77.8 (14), 100.0 (18) and 80.0% (12) respectively. Similarly, the average number of pups born per litter among the four treatments was 11.8, 9.3, 10.1, and 9.8. When the chow treatment (1 and 3) and the fescue treatments (2 and 4) were pooled and compared, the percent pregnancy was 100.0 (n = 36) and 78.8 (n = 26), and the pups born per litter (means +/- SEM) were 11.0 +/- 0.5 and 9.5 +/- 0.6, respectively. Also the intervals between the three litters born during the 60-d cohabitation period were 21.6 +/- 1.1 and 24.5 +/- 0.9 d for the chow and fescue treatments, respectively. The results point out that 40 and 60% infected fescue seed in the diet of mice does influence (P < 0.05) their reproductive capacity as measured by percent pregnancy and litter size.     

Molecular evolution in Hawaiian drosophilids

The evolutionary relationships of the Hawaiian drosophilids have been studied by several molecular techniques. Immunological measurements have determined some of the distances between the major groups. More detailed studies have used protein polymorphism, DNA hybridization, DNA restriction enzyme analysis and DNA sequence studies of both nuclear and mitochondrial genomes. These studies indicate both the strengths and the weaknesses of the various methods and suggest new ways to examine phylogenetic relationships and question some of the accepted ph ylogenies.