Molecular characterization of an additional shrimp hyperglycemic hormone: cDNA cloning, gene organization, expression and biological assay of recombinant proteins.
The crustacean eyestalk CHH/MIH/GIH neurohormone gene family represents a unique group of neuropeptides identified mainly in crustaceans. In this study, we report the cloning and characterization of the cDNA and the gene encoding the hyperglycemic hormone (MeCHH-B) of the shrimp Metapenaeus ensis. The amino acid sequence of MeCHH-B shows 85% identity to that of MeCHH-A (formerly MeCHH-like neuropeptide). Two separate but identical MeCHH-B genes were identified in the genome of shrimp by library screening and they are located on different CHH gene clusters. The organization of the MeCHH-B gene is identical to other members of the CHH/MIH/GIH neurohormone family. MeCHH-B is expressed at a constant level in the eyestalks of juveniles and mature females. Unlike the MeCHH-A gene, a low level of MeCHH-B transcripts can also be detected in the central nervous system. Interestingly, the expression pattern of MeCHH-B in the eyestalk of vitellogenic females is reversed to that of the MeCHH-A gene. At the middle stage of gonad maturation, a minimum level of MeCHH-B transcript was recorded and a maximum level of MeCHH-A transcript was detected. Recombinant proteins for MeCHH-A and MeCHH-B were produced by a bacterial expression system. The hemolymph glucose level of bilaterally eyestalk-ablated shrimp increased two-fold 1 h after the rCHH injection and then returned to normal after 2 h. The hyperglycemic effect of these fusion proteins is comparable to that of de-stalked shrimp injected with crude extract from a single sinus gland.
Gu
P L
PL
Department of Zoology, The University of Hong Kong, Pokfulam Road, Hong Kong, China.
Yu
K L
KL
Chan
S M
SM
D000595:Amino Acid Sequence; D000818:Animals; D060829:Arthropod Proteins; D001419:Bacteria / Q000378:metabolism; D001483:Base Sequence; D015152:Blotting, Northern; D015139:Blotting, Southern; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000737:chemistry; D033364:Decapoda / Q000235:genetics* / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D006066:Gonads / Q000502:physiology; D006458:Hemolymph / Q000378:metabolism; D006943:Hyperglycemia / Q000378:metabolism; D007447:Invertebrate Hormones / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D008969:Molecular Sequence Data; D009928:Organ Specificity; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment
D060829:Arthropod Proteins; C116855:CHH-like protein, shrimp; D018076:DNA, Complementary; D007447:Invertebrate Hormones; D011993:Recombinant Fusion Proteins