A spiroplasma associated with tremor disease in the Chinese mitten crab (Eriocheir sinensis).
An epidemic of tremor disease has been a serious problem in Chinese mitten crabs, Eriocheir sinensis, in China in recent years. The disease-causing agent was previously considered to be a rickettsia-like organism. Here, analysis of the 16S rRNA gene sequence, light and electron microscopy and cultivation in vitro were used to identify the agent. Sequence analysis of the 16S rRNA gene found it to have 98 % identity with that of Spiroplasma mirum. The agent was able to be passed through membrane filters with pores 220 nm in diameter and could be cultivated by inoculating the yolk sac of embryonated chicken eggs and M1D medium. Rotary motion and flexional movement were seen by light microscopy, and electron microscopy showed that the organism had a helical morphology and lacked a cell wall. The organism produced small colonies with a diameter of 40-50 microm after 17-25 days of incubation on solid M1D medium. The agent was found in blood cells, muscles, nerves and connective tissues of crabs inoculated with a filtrate of yolk sacs or with cultures grown in M1D medium, and it was similar in structure to those grown in eggs and cultivation broth. Disease was reproduced by experimental infection with the cultivated organisms. This study has demonstrated that the causative agent of tremor disease in the Chinese mitten crab is a member of the genus Spiroplasma. This is believed to be the first time a spiroplasma has been found in a crustacean. These findings are not only significant for studies on pathogenic spiroplasmas, but also have implications for studies of freshwater ecology.
Wang
Wen
W
Department of Biological Science and Technology, Nanjing University, Nanjing 210093, PR China.|Key Laboratory for Bioresources Technology of Jiangsu Province, College of Biological Sciences, Nanjing Normal University, Nanjing 210097, PR China.
Wen
Bohai
B
Department of Microbiology, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, PR China.
Gasparich
Gail E
GE
Department of Biological Sciences, Towson University, Towson, MD 21252, USA.
Zhu
Ningning
N
Key Laboratory for Bioresources Technology of Jiangsu Province, College of Biological Sciences, Nanjing Normal University, Nanjing 210097, PR China.
Rong
Liwen
L
Key Laboratory for Bioresources Technology of Jiangsu Province, College of Biological Sciences, Nanjing Normal University, Nanjing 210097, PR China.
Chen
Jianxiu
J
Department of Biological Science and Technology, Nanjing University, Nanjing 210093, PR China.
Xu
Zaikuan
Z
Jiangsu Freshwater Fishery Research Institute, Nanjing 210017, PR China.
D000818:Animals; D001769:Blood / Q000382:microbiology; D003386:Brachyura / Q000382:microbiology*; D002473:Cell Wall / Q000648:ultrastructure; D002642:Chick Embryo; D003238:Connective Tissue / Q000382:microbiology; D003470:Culture Media / Q000737:chemistry; D004269:DNA, Bacterial / Q000737:chemistry / Q000302:isolation & purification; D004275:DNA, Ribosomal / Q000737:chemistry / Q000302:isolation & purification; D020459:Genes, rRNA; D008969:Molecular Sequence Data; D009068:Movement; D009132:Muscles / Q000382:microbiology; D009474:Neurons / Q000382:microbiology; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid; D013149:Spiroplasma / Q000166:cytology / Q000235:genetics / Q000302:isolation & purification* / Q000502:physiology; D015017:Yolk Sac / Q000382:microbiology
D003470:Culture Media; D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S