Lens protein phylogeny: immunocrossreactivity of vertebrate lens antigens to anti-shark crystallin antibody.

Antisera prepared against total water-soluble lens proteins of the shark, Scoliodon sorrakowah were reacted with homologous antigen and analysed reaction products by immunoelectrophoresis (IE) and two dimensional crossed antigen-antibody electrophoresis (2D-CE). On IE, shark antigens formed 5 precipitin lines including 1 alpha, 3 beta and 1 gamma crystallins and on 2D-CE 3 alpha, 6 beta and 6 gamma peaks accounting for 8%, 27% and 65% antigen in the respective group were obtained from the total crystallins. Using anti-shark antisera, the immunocrossreactivity of lens proteins from 6 Chondropterygii, 23 teleosts and 16 higher vertebrates was examined by IE. It is found that beta crystallins are the most conserved and crossreact with all vertebrate classes, whereas gamma crystallin crossreactivity is specific to the class Pisces and alpha crystallins are least conserved and their crossreactivity is confined to subclass Chondropterygii. Based on IE patterns, a phylogenetic tree is constructed which demonstrates the intrafamily closeness except in case of adaptive radiation.

Multiple neural inductions in area opaca by grafts of the Hensen's node do not retard host chick embryo development.

Four hundred and forty four full primitive streak stage chick embryos were cultured in vitro and 261 were transplanted with 1, 3 or 5 Hensen's nodes in the area opaca. Irrespective of the number of grafts, neural induction was observed in 90% cases. The development of control and grafted embryos and the size of blastoderm area were monitored at the time of grafting and after 20 hr. We find that the induced neural tissue and differentiated tissue of graft-origin neither fuse with the host embryonic axis, nor retard its development.

Physicochemical characterization and phylogenetic comparison of fish lens proteins.

The composition of soluble eye lens proteins from four chondropterygiian and fourteen teleostean fishes were analyzed for heterogeneity in MW and pI. Lens proteins from all the fish species studies are distributed in the pI range 4.3-9.0 with polypeptides in the range 17,500-31,000 Da. Phylogenetic trees are constructed based on the observations.

Rat liver chromatin digested in situ with endogeneous Mg(2+)-dependent deoxyribonuclease exhibits two distinct DNA repeats.

Incubation of rat liver nuclei in the presence of 1.0-5.0 mM Mg2+ at 37 degrees C releases oligonucleosomes containing at least two distinct chromatin-DNA repeat elements. The 'short' repeat is derived from the dimer to pentamer series, while the 'long' repeat is found in the monomer and hexamer to decanucleosomes. Both repeat lengths decrease during enzymatic hydrolysis but in 5.0 mM Mg2+, which is optimal concentration, the 'long' repeat is degraded faster.

Isonicotinic acid hydrazide inhibits cell population growth during teratogenesis of chick embryo.

In chick embryos treated with a 4 hr pulse of 7.2 X 10(-5) M isonicotinic acid hydrazide (INH) the cell population growth is inhibited with an increased population doubling time. Teratogenised blastoderm cells complete their ongoing cell cycle and arrest in G1 phase. A chase with an equimolar concentration of pyridoxal-5-phosphate restores the growth rate after a lag of 4 hr equivalent to the duration of treatment with INH. Presumptive mesoblast cells invaginated through the primitive streak and neuroectoblast cells induced prior to the application of INH differentiate, while the teratogen inhibits morphogenesis and organization of organ primordia.

Cell population growth in chick blastoderms cultured in vitro.

Primitive streak stage chick blastoderms were cultured in vitro up to 30 hr by New's technique. Chick blastoderms reaching stages 4 to 12 in vitro cultures and in ovo were harvested and homogenized to release cell nuclei. Fluorescent ethidium bromide-stained nuclei in homogenates were counted in Neubauer's chamber and the size of total blastoderm cell population was determined. Linear regression analysis revealed that both in ovo and in vitro chick blastoderm cell population grows in a biphasic manner with comparable cell population doubling times and the morphogenesis is not affected in vitro during the culture period.