Parthenogenesis, polyploidy and reproductive seasonality in the Taiwanese mountain earthworm Amynthas catenus (Oligochaeta, Megascolecidae)

Amynthas catenusTsai et al., 2001 is a terrestrial earthworm belonging to the Pheretima complex of the family Megascolecidae. It is endemic to Mt. Hohuan of central Taiwan at elevations of 2985-3004 m. Its reproductive organs showed various stages of degeneration in the present study. The spermathecae varied from being absent (athecal) to three pairs in VI-VIII (sexthecal), and the prostate glands from a large, symmetrical pair to complete absence. For the 44 specimens examined from May 2008 to May 2010, there were 47.7% athecals, 36.4% sexthecals and 15.9% intermediates. Results of a flow cytometric analysis showed that there were three DNA ploidy levels - diploid, triploid and tetraploid (2n, 3n, and 4n) - for the athecals but only diploid for the sexthecals. The intermediates consisted of diploids and triploids. The diploids had 2n = 112 and the triploids 3n = 168. The haploid chromosome number of A. catenus was 56. Spermatogenesis occurred throughout the year with the highest activity in summer for both athecals and sexthecals, but the number of mature ova peaked in summer for the athecals and in spring for the sexthecals. There was no significant difference in mean number of mature ova produced between the athecals and the sexthecals, but the sexthecals had significantly higher spermatogenetic activity than the athecals. For all specimens examined, sperm were present in testes and seminal vesicles but not in spermathecae, an indication of parthenogenesis in the species.     

Nanosize of zinc oxide and the effects on zinc digestibility,growth performances,immune response and serum parameters of weanling piglets

The aim of this study was to investigate the effect of dietary supplementation of nanosize zinc on zinc digestibility, growth performances, immune response and serum parameters of weanling piglets. Ninety‐six LYD weanling piglets were assigned to control, zinc oxide (ZnO), organic‐Zn (Zn‐methionine) and nanosize ZnO (nano‐Zn) groups with four replicates. The zinc was at the 120 mg/kg level in the treatment group's diet, while the control group's was 80 mg/kg Zn. The experiment results indicated that the nano‐Zn and organic‐Zn groups had significantly higher Zn digestibility compared to the ZnO and control groups. For the immune response traits, the IgG level and goat red blood cells (GRBC) antibody titer were nano‐Zn and organic‐Zn>ZnO>control; in the phytohemagglutinin (PHA) challenge test result, nano‐Zn>organic‐Zn>ZnO>control; in regard to the γ‐globulin level, nano‐Zn and organic‐Zn>ZnO and control, with significant difference between groups. In the serum parameters aspect, serum Zn concentration in nano‐Zn and organic‐Zn groups were higher than in the ZnO and control groups, serum growth hormone concentration was increased in the nano‐Zn group than in the other groups. In conclusion, nanosize zinc oxide for dietary supplementation can increase zinc digestibility, serum growth hormone levels and carbonic anhydrase activity and enhance the immune response of weanling piglets.     

Genetic characteristics of Streptococcus dysgalactiae isolated from cage cultured cobia,Rachycentron canadum (L.)

Disease outbreaks occurred during 2007–2013 in Taiwan with 2.5–10% mortality among the cage cultured cobia, Rachycentron canadum (L.), characterized by the presence of polyserositis, pericarditis and peritonitis. The micro‐organisms isolated from internal organs were Gram‐positive cocci. The isolates were confirmed as Streptococcus dysgalactiae by a polymerase chain reaction assay that yielded the expected specific 259 bp amplicon. Additionally, partial sequence of the 16S–23S rDNA intergenic spacer region of the GCS strain isolates from fish was also compared and produced 100% sequence identity with S. dysgalactiae (GenBank accession number AB252398 ). The genetic characterization was then determined by pulsed‐field gel electrophoresis (PFGE) analysis. Based on PFGE, the Apa I or Sma I digestion patterns of chromosomal DNA of these isolates were grouped into three main clusters. Taiwanese strains were divided into two clusters, and the tet(M) gene was detected in cluster 1 (pulsotypes: A1–A2 and S1–S3), but not in cluster 2 strains (pulsotypes: A3–A4 and S4–S5). Three Japanese strains from amberjack, Seriola dumerili (Risso), were grouped into cluster 3 (pulsotypes: A5–A7 and S6–S8) and displayed no mortality to cobia in the challenge experiment. Conversely, Taiwanese strains from cobia and snubnose pompano, Trachinotus blochii (L.), displayed a mortality rate of 50–87.5% in cobia.     

中国水稻三化螟防治研究的进展

在中国为害水稻較重的螟虫已知有6种,以三化螟 Tryporyza incertulas (Wlk.)最为重要,分布于我国中南部稻区。本文阐述了气候、食料、水稻栽培制度和生物等因素对三化螟种群数量变动的影响,并指出作为螟虫食料的水稻及其栽培制度的作用更为明显。研究証明,三化螟的产卵、侵入、成活、繁殖和为害都与水稻的生育期有密切关系,水稻的分蘖期及孕穗期,都是水稻最易受害的生育期,在这两个时期被害,会造成枯心或白穗;而秧田期、移植至回青期、圓稈期和成熟期都对螟虫不利。螟虫的发生基数和生活环境条件,密切影响种群数量的变动,而这些都受水稻栽培制度的影响。发生基数决定于春季螟虫的有效虫源,其数量的大小对当年的螟虫,尤其对第一、二代的发生量有密切关系。螟害程度主要决定于:(1)种群数量和(2)水稻最易受害的生育期与螟虫盛发期配合程度的综合作用。为了加強防治,各地区必须因地制宜,利用耕作栽培措施,一方面尽可能消灭虫源、压低发生基数、控制以后各代螟虫的发生;另一方面力求改进栽培技术、調节水稻生育期,恶化螟虫的生活条件,避免或減輕螟害。化学防治也是治螟的一項重要措施。目前广泛应用的药剂是6％丙体六六六,每亩用量在防治枯心时为1.5斤,防治白穗为2斤。主要的施药方法为泼浇和撒毒土,两者对防治枯心的效果都很好;撒毒土防治白穗的效果虽稍差,但操作簡便易行。在螟虫发生期內,适值分蘖和孕穗的水稻田一般都要施药;但預测螟害低于1％的田块,可不防治。防治枯心的施药适期一般在孵化高峯前1—2天天开始,如虫量很大,要提前到盛孵始期用药。防治白穗的施药适期是:在蚁螟盛孵前孕穗的水稻,普通在盛孵始期开始施药;蚁螟盛孵后孕穗的水稻,在孕穗始期开始用药。稻螟是我国长期以来的一种严重害虫,解放前因螟害常年損失稻谷10％以上。解放后,在党和政府的領导下,科学技术有了显著的进展,治螟工作貫彻了“防治并举、以防为主”的方針,“以农业防治为基础,重点使用药剂綜合防治”的策略;采用了准确的預测預报;开展了群众性的防治活动,基本上控制了螟虫的危害,1663年的螟害率已压低到2％左右,不少地区已降低到1％以下。这都是在总路线、大跃进、人民公社三面紅旗光輝照耀下,領导、技术人員、群众三結合所取得的成果的     

Radial growth of <Emphasis Type="Italic">Cinnamomum kanehirae</Emphasis> Hayata displays a larger temperature sensitivity in dominant than codominant trees

Key message

The radial wood growth curves of Cinnamomum kanehirae Hayata (an endangered species of subtropical Taiwan) exhibit an S shape. The dominant trees displayed a larger radial growth than the codominant trees, and their growth was more sensitive to air temperature.

Context

Knowledge of wood radial growth is important for evaluating the factors that limit tree growth performance. The relevant experiments have mostly been conducted in cold and temperate ecosystems, but rarely in subtropical ecosystems.

Aims

In this study, we aimed to construct a unified radial growth model for Cinnamomum kanehirae Hayata and to identify its sensitivity to temperature.

Methods

The wood radial increments were quantified for 3 years by either pinning or microcoring. The radial wood growth curves were modelled integratively by semiparametric regression and individually by curve fitting. The effects of tree social class, interannual and environmental factors on radial growth were analysed quantitatively.

Results

A unified S-shaped growth model for C. kanehirae was successfully constructed. By including the social class effect, the model was significantly improved. The maximum radial increment (A) was significantly correlated with the maximum growth rate (μ); both A and μ were significantly higher in dominant than in codominant trees. The time-varying radial growth rate was more sensitive to air temperature in dominant than in codominant trees.

Conclusion

Semiparametric models revealed an S-shaped growth curve of C. kanehirae and confirmed the higher temperature sensitivity of dominant trees compared to codominant trees in humid subtropical areas.

     

Acceleration of post‐mortem changes in Tsaiya duck (Anas platyrhynchos) breast muscle by lactic acid marination

1. The effect of lactic acid marination at 5°C on post mortem changes in breast muscle pectoralis major of spent layer Tsaiya duck was studied.

2. Myofibrils were prepared from 0.1 M and 0.2 M lactic acid marinated muscle and control (non‐marinated samples) sampled at 0, 1, 3, 7 and 14 d post mortem.

3. Changes in myofibril fragmentation index (MFI), myofibrillar proteins and Z‐line structure were examined.

4. Marination of duck breast muscle in lactic acid at 5°C enhanced fragmentation of myofibrils and degradation of myofibrillar proteins and Z‐line structure as compared to control samples.

5. In summary, lactic acid marination at 5°C can accelerate the post mortem degradation of myofibrils in Tsaiya duck breast muscle.     

Multiplex nested-polymerase chain reaction for the simultaneous detection of Aeromonas hydrophila, Edwardsiella tarda, Photobacterium damselae and Streptococcus iniae, four important fish pathogens in subtropical Asia

A multiplex nested-polymerase chain reaction (PCR)-based (m-nested PCR) method was developed for simultaneous detection of four important freshwater/marine fish pathogens in subtropical Asia, including Aeromonas hydrophila, Edwardsiella tarda, Photobacterium damselae and Streptococcus iniae . The specificity of the oligonucleotide primers used for PCR detection was confirmed to generate specific amplicons for the corresponding pathogens. Moreover, non-specific amplicons were observed when the primers were tested using pure DNA extracted from 31 related bacterial strains belonging to 23 species or tissue homogenates of infected tilapia. This m-nested PCR approach could detect 19 colony forming unit (CFU) for A. hydrophila , 62 CFU for E. tarda , 280 CFU for P. damselae subsp. piscicida and 179 CFU for S. iniae in infected tilapia kidney homogenates, consistent with the results derived from bacteriological methods. The assay described in this paper is a sensitive and effective method for simultaneous detection of multiple fish pathogens.     

Evaluation of plant seedling water stress using dynamic fluorescence index with blue LED-based fluorescence imaging

A dynamic fluorescence image index system capable of non-destructive assessment of water stress in cabbage seedlings was developed. The quenching curves of chlorophyll fluorescence characteristic to the plant's water stress status under reduced excitation energy were acquired via a multispectral imaging system. The dynamic fluorescence index (DFI), a fluorescence index derived from quantitative modeling of the quenching curves in this study, was found superior to conventional indices such as the fluorescence decrease ratio (Rfd) in evaluating water stress status in cabbage seedlings, with respect to due mainly to its significantly reduced measuring time and enhanced precision of the chlorophyll fluorescence responses. The best results of the quantitative model to predict water stress status of seedlings using the dynamic fluorescence index were r = 0.944 and SEE = 0.286 MPa using the 720 nm channel. The blue (460 nm) LED-excited fluorescence multispectral imaging system (FMSIS) coupled with DFI provides a powerful research tool for plant physiology studies as well as for improving greenhouse and agriculture management practices where quantitative assessment of water potential in leafy plants is critical.