ABSTRACT
More than 20 species of the entomopathogenic nematode Steinernema have been described; to date, all reproduce exclusively by cross-fertilization of male and female individuals. Steinernema sp. strain T87 from Indonesia was found to consist largely of self-fertile hermaphrodites. Progeny were produced by morphological females both in insects (Galleria mellonella) and in hanging drops of insect haemolymph inoculated with a single infective juvenile. Sperm were present in the oviduct of unmated morphological females. Approximately 1% of infective juveniles developed into males, and males were also present in the second generation where they constituted 1-6% of the population. Under the same conditions the related species Steinernema longicaudum strain CB2B displayed typical steinernematid reproduction: cross-fertilization and a 1:1 sex ratio. It is argued that the development of hermaphroditism in Steinernema sp. T87 represents convergent evolution with Heterorhabditis, the other major genus of entomopathogenic nematode.
Subject(s)
Biological Evolution , Nematoda/classification , Animals , Female , Fertility , Indonesia , Male , Nematoda/genetics , Nematoda/physiology , Reproduction , Sex RatioABSTRACT
Longitudinal movement of the radius, in relation to the ulna, occurring during abduction and adduction of the elbow, and during radial and ulnar deviation of the wrist, was examined roet-genographically on five students. A fixation device was designed to stabilize the humerus while the passive movements were carried out, and all measurements were done with the arm in 0° extension. The average movement from full adduction to full abduction was 10.4° and, at the same time, the radius moved an average of 1.6 mm distally in relation to the ulna. When the wrist was moved from full radial deviation to full ulnar deviation the radius moved an average of 0.1 mm in relation to the ulna. The importance of assessing passive accessory movements at the elbow in the examination and treatment of elbow lesions is discussed.
