The crayfish Procambarus clarkii CRY shows daily and circadian variation

The crayfish Procambarus clarkii CRY shows daily and circadian variation.

The circadian rhythms of crayfish are entrained by blue light, through putative extra retinal photoreceptors. We investigated the presence and daily variation of CRY, a protein photosensitive to blue light spectra and ubiquitous in animals and plants, in the putative pacemakers of Procambarus clarkii, namely the eyestalk and brain, at different times of the 24 h light:dark cycles. Using differe...

Spermiogenesis in the Crayfish (procambarus Clarkii)

The sperm of the crayfish, Procambarus clarkii, is relatively simple among decapod sperm and was described in the first paper of this series (28). The present paper details the development of this sperm as followed with the light and electron microscopes. The process is divided into six stages for purposes of description. The main points of interest discussed are the absence of mitochondria or ...

Crayfish (Procambarus clarkii) Effects on Lentic Lake Water Quality

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Repetitive DNA sequence from the crayfish Procambarus clarkii.

A repetitive DNA element was obtained from a crayfish genomic library while attempting to isolate the gene for the pigment concentrating hormone (PCH) with an oligonucleotide probe. The probe was directed to the coding region of the octapeptidic hormone deduced from the amino acid sequence of PCH (1). The isolated clone contained a 14 nucleotide sequence tandemly repeated 30 times; eleven nucle...

Red Swamp Crayfish (procambarus Clarkii) in River Nile, Egypt