Biomaterial Database

Differential expression of the two delta-crystallin genes in lens and non-lens tissues: shift favoring delta 2 expression from embryonic to adult chickens. 1993

X Li, and P S Zelenka, and J Piatigorsky

Laboratory of Molecular and Developmental Biology, National Eye Institute, National Institutes of Health, Bethesda, Maryland 20892.

Chicken argininosuccinate lyase (ASL)/delta-crystallin, a lens enzyme-crystallin, is encoded in two linked genes (delta 1 and delta 2); only the delta 2 polypeptide contains ASL activity. Here we have quantified delta 1- and delta 2-crystallin mRNA in the lens, cornea, neural retina, heart, and brain at different stages of embryonic development and in 1-wk-old and 1-yr-old chickens by the polymerase chain reaction using internal delta 1 and delta 2 RNA standards. The delta 1/delta 2 mRNA ratio differed for every tissue and was regulated during development. In the embryo there was more delta 1 than delta 2 mRNA in the lens (50-100 times), cornea (3-4 times), and neural retina (2-20 times), about equal amounts of delta 1 and delta 2 mRNA in the heart, and more delta 2 mRNA in the brain (15 times). delta 1-Crystallin mRNA differentially decreased in every tissue after hatching; by contrast, the delta 2 mRNA remained about the same except for the lens, where it decreased 50-fold between 1 wk and 1 yr after hatching. In the 1-yr-old chicken, the delta 2/delta 1 mRNA ratios were 7 in the lens, 175 in the cornea, 22 in the neural retina, 107 in the heart, and 136 in the brain, indicating that delta 2-crystallin is strongly favored in all adult tissues of the chicken. The excess of delta 1 to delta 2 mRNA in the embryonic lens, cornea, and neural retina is intriguing, and suggests some connection with developing transparent eye tissues. Finally, we raise the possibility that expression of both delta-crystallin genes may create tetrameric ASL isoenzymes (perhaps with different specific activities). The unexpected predominance of delta 2 mRNA in the 1-yr-old lens suggests that both the enzymatic and refractive functions of ASL/delta-crystallin are operative and spatially separated, with the enzymatic role present in the cortical fibers and the refractive role in the center of the lens.

UI	MeSH Term	Description	Entries
D007908	Lens, Crystalline	A transparent, biconvex structure of the EYE, enclosed in a capsule and situated behind the IRIS and in front of the vitreous humor (VITREOUS BODY). It is slightly overlapped at its margin by the ciliary processes. Adaptation by the CILIARY BODY is crucial for OCULAR ACCOMMODATION.	Eye Lens,Lens, Eye,Crystalline Lens
D008969	Molecular Sequence Data	Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.	Sequence Data, Molecular,Molecular Sequencing Data,Data, Molecular Sequence,Data, Molecular Sequencing,Sequencing Data, Molecular
D009206	Myocardium	The muscle tissue of the HEART. It is composed of striated, involuntary muscle cells (MYOCYTES, CARDIAC) connected to form the contractile pump to generate blood flow.	Muscle, Cardiac,Muscle, Heart,Cardiac Muscle,Myocardia,Cardiac Muscles,Heart Muscle,Heart Muscles,Muscles, Cardiac,Muscles, Heart
D012160	Retina	The ten-layered nervous tissue membrane of the eye. It is continuous with the OPTIC NERVE and receives images of external objects and transmits visual impulses to the brain. Its outer surface is in contact with the CHOROID and the inner surface with the VITREOUS BODY. The outer-most layer is pigmented, whereas the inner nine layers are transparent.	Ora Serrata
D001921	Brain	The part of CENTRAL NERVOUS SYSTEM that is contained within the skull (CRANIUM). Arising from the NEURAL TUBE, the embryonic brain is comprised of three major parts including PROSENCEPHALON (the forebrain); MESENCEPHALON (the midbrain); and RHOMBENCEPHALON (the hindbrain). The developed brain consists of CEREBRUM; CEREBELLUM; and other structures in the BRAIN STEM.	Encephalon
D001923	Brain Chemistry	Changes in the amounts of various chemicals (neurotransmitters, receptors, enzymes, and other metabolites) specific to the area of the central nervous system contained within the head. These are monitored over time, during sensory stimulation, or under different disease states.	Chemistry, Brain,Brain Chemistries,Chemistries, Brain
D002642	Chick Embryo	The developmental entity of a fertilized chicken egg (ZYGOTE). The developmental process begins about 24 h before the egg is laid at the BLASTODISC, a small whitish spot on the surface of the EGG YOLK. After 21 days of incubation, the embryo is fully developed before hatching.	Embryo, Chick,Chick Embryos,Embryos, Chick
D002645	Chickens	Common name for the species Gallus gallus, the domestic fowl, in the family Phasianidae, order GALLIFORMES. It is descended from the red jungle fowl of SOUTHEAST ASIA.	Gallus gallus,Gallus domesticus,Gallus gallus domesticus,Chicken
D003315	Cornea	The transparent anterior portion of the fibrous coat of the eye consisting of five layers: stratified squamous CORNEAL EPITHELIUM; BOWMAN MEMBRANE; CORNEAL STROMA; DESCEMET MEMBRANE; and mesenchymal CORNEAL ENDOTHELIUM. It serves as the first refracting medium of the eye. It is structurally continuous with the SCLERA, avascular, receiving its nourishment by permeation through spaces between the lamellae, and is innervated by the ophthalmic division of the TRIGEMINAL NERVE via the ciliary nerves and those of the surrounding conjunctiva which together form plexuses. (Cline et al., Dictionary of Visual Science, 4th ed)	Corneas
D003459	Crystallins	A heterogeneous family of water-soluble structural proteins found in cells of the vertebrate lens. The presence of these proteins accounts for the transparency of the lens. The family is composed of four major groups, alpha, beta, gamma, and delta, and several minor groups, which are classed on the basis of size, charge, immunological properties, and vertebrate source. Alpha, beta, and delta crystallins occur in avian and reptilian lenses, while alpha, beta, and gamma crystallins occur in all other lenses.	Lens Proteins,Crystallin,Eye Lens Protein,Lens Protein, Eye,Protein, Eye Lens,Proteins, Lens