Cytokinin-induced switch in development in excised cotyledons of radiata pine cultured in vitro

Cotyledons of Pinus radiata D. Don were cultured under shoot-forming (plus cytokinin) and elongating (minus cytokinin) conditions. Using. autoradiographic and precursor incorporation techniques, the sites and rate of macromolecular synthesis were examined during the first five days in culture. Active incorporation of ³H-thymidine, ³ H-uridine and ³H-leucine occurred. In shoot-forming cotyledons the incorporation became preferentially located in the epidermal and sub-epidermal cell layers in contact with the medium. In elongating cotyledons, in contrast, incorporation was randomly distributed, and the amount of incorporation declined with time. Biochemically, differences in DNA, RNA and total protein synthetic patterns were observed. In elongating cotyledons the rates of RNA and protein synthesis were higher during the first 48 h than in shoot-forming tissues, after which the synthetic rates were similar. Two peaks of newly formed DNA were observed in both tissues. These findings indicate that the cytokinin-induced changes in developmental pathways began within 24 h in culture.     

Direct interaction of tricyclic antidepressants with opiate binding sites in the bovine adrenal medulla

This note reports the interaction of three currently used tricyclic antidepressant drugs (clomipramine, imipramine and amitriptyline) with delta, mu and kappa opioid binding sites in the bovine adrenal medulla. Clomipramine was the only drug interacting with delta and mu sites. On the contrary, all three drugs showed a significant interactions with subtypes of the kappa binding site. Clomipramine was the most active on the kappa 2 and kappa 3 subtypes while amitriptyline showed the highest interaction with the kappa 1 subtype. On the contrary the tricyclic cyproheptadine did not present any interaction with opioid binding sites in our system. This interaction between tricyclic antidepressants and opioid binding sites might be the origin of their analgesic action.     

Activity of phenol oxidases at the puparium formation stage in development of nineteen lozenge mutants of Drosophila melanogaster

Phenol oxidase activity of activated A₁ and A₂ (A₃) electrophoretic components from 19 lozenge mutant and three lozenge double mutant strains was compared to that of wild type flies. Melanin production by the activated A components with tyrosine as substrate was compared to activity in the same acrylamide gels with dopa as substrate. Melanin production decreased, first in the A₁ band and then in the A₂ (A₃) band, with increased morphological expression of the mutant genes. No melanin bands were obtained with either substrate in five of the more severely affected mutants. A possible correlation between phenol oxidase activity and quinone production necessary for normal development of eyes, female accessory sex organs, and claws is discussed.Supported by PHS grant AM-08331-05.     

Juvenile Pernicious Anaemia and Hypothyroidism. A Family Study

A man presented with the sudden onset of pernicious anaemia at the age of 21. He had been treated for hypothyroidism since the age of 6. His father and only paternal aunt were also found to have pernicious anaemia. Gastric and thyroid antibody studies showed one or more antibodies to be present in all three subjects, as well as in the patient''s mother.     

Sites of synthesis of plasma proteins in the foetal rat

1. The foetal rat of 16 or more days incorporates ¹⁴C-labelled amino acids into all the demonstrable plasma protein fractions in vivo. 2. Slices of foetal rat liver incubated in vitro incorporate ¹⁴C-labelled amino acids into the main plasma protein fractions, including the foetal-specific `post-albumin'. 3. Slices of placenta are unable to incorporate ¹⁴C-labelled amino acids into plasma proteins in vitro. 4. Liver slices from maternal rats incubated in vitro incorporate ¹⁴C-labelled amino acids into plasma proteins. The presence of post-albumin cannot be demonstrated after incubation. 5. Liver slices from foetal rats, but not from adult rats, contain demonstrable amounts of haemoglobin into which ¹⁴C-labelled amino acids are incorporated.