Ultrastructural evidence of oestradiol receptor by immunochemistry

Antiserum against calf uterus oestradiol receptor has been used for detecting oestradiol receptor in rat pituitary cells at the ultrastructural level after immunochemical reaction according to Sternberger. The gonadotropic, lactotropic and somatotropic cells were positive, but not the thyrotropic and corticotropic cells. In peripubertal and adult rats, both cytoplasmic and nuclear receptors were seen, but in a long-term castrated rat, the receptor was found only in the cytoplasm. After oestradiol administration to 21-day-old animals, the cytoplasmic receptor decreased and the nuclear receptor increased in gonadotropic cells, supporting the concept of hormone-receptor complex translocation. Antibodies against α1-foetoprotein demonstrated the presence of this oestrogen-binding plasma protein in all pituitary cells, but only in the cytoplasmic area. These results and the immunological controls related to antibody specificity give the first evidence of steroid receptor at the ultrastructural level.     

Late replication patterns in adult and embryonic mice carrying Searle's X-autosome translocation

Bromodeoxyuridine-dye technique analysis of X chromosome DNA synthesis in female adult and fetal mice carrying the balanced form of the T(X; 16) 16H translocation demonstrated that the structurally normal X chromosome was late replicating (and hence presumably inactive) in 93% of the adult cells and 99% of the 9-day embryo cells, with the X¹⁶ chromosome late replicating in the remaining cells. We conclude from these results that in T16H/+ females either there is preferential inactivation of the normal X chromosome or that, if inactivation is random, cell selection takes place before 9 days of development. Two 9-day female embryos with an unbalanced karyotype were also studied; both had two late-replicating chromosomes in most of their cells, one being the chromosome 16^X, the other a normal X chromosome. These results, together with the presence of a late-replicating X¹⁶ chromosome in T16H/+ adult and fetal mice, support the concept that more than one inactivation center is present on the X chromosome of the mouse because the X¹⁶ and the 16^x chromosomes can be late replicating.     

Chromosome banding in amphibia

The distribution of constitutive heterochromatin on the chromosomes of Triturus a. alpestris, T. v. vulgaris and T. h. helveticus (Amphibia, Urodela) was investigated. Sex-specific chromosomes were determined in the karyotypes of T. a. alpestris (chromosomes 4) and T. v. vulgaris (chromosomes 5). The male animals have one heteromorphic chromosome pair, of which only one homologue displays heterochromatic telomeres in the long arms; the telomeres of the other homologue are euchromatic. This chromosome pair is always homomorphic and without telomeric heterochromatin in the female animals. There is a highly reduced crossing-over frequency between the heteromorphic chromosome arms in the male meiosis of T. a. alpestris; in T. v. vulgaris no crossing-over at all occurs between the heteromorphic chromosome arms. No heteromorphisms between the homologues exist on the corresponding lampbrush chromosomes of the female meiosis. In T. h. helveticus no sex-specific heteromorphism of the constitutive heterochromatin could be determined. The male animals of this species, however, already possess a chromosome pair with a greatly reduced frequency of chiasma-formation in the long arms. The C-band patterns and the pairing configurations of the sex-specific chromosomes in the male meiosis indicate an XX/XY-type of sex-determination for the three species. A revision of the literature about experimental interspecies hybridizations, gonadic structure of haploid and polyploid animals, and sex-linked genes yielded further evidence in favor of male heterogamety. The results moreover suggest that the heterochromatinization of the Y-chromosome was the primary step in the evolution of the sex chromosomes.     

Selective lesions of acinar pancreatic cells in rats poisoned with abrin

Rats poisoned with abrin (2.5 micrograms/100 g body weight) died within 36 h with severe necrosis of acinar pancreatic cells. Incorporation in vivo of labelled amino acids into pancreatic protein was greatly impaired 6 h after poisoning. Microsomes isolated from the pancreas of poisoned rats at 6 h had a reduced capacity for protein synthesis in vitro. Incorporation in vivo of orotic acid into pancreatic RNA was decreased 12 h after poisoning.     

Aspects of the cross transmission to Galleria mellonella of a Baculovirus from the alfalfa looper, Autographa californica

The nuclear polyhedrosis virus originally isolated from the alfalfa looper, Autographa californica, was successfully transmitted to the greater wax moth, Galleria mellonella. Both the many polyhedra per nucleus (MP) and the few polyhedra per nucleus (FP) plaque variants of this virus were found to be infective when injected intracoelomically. When polyhedra of each plaque variant were fed to G. mellonella larvae, a difference in response was observed; the MP plaque variant was estimated to be 30 times more infective than the FP variant.     

The characteristics of shuttling RNAs confirmed

Shuttling RNAs are recognized as molecules that migrate against steep concentration gradients from one nucleus (through the cytoplasm) into another nucleus in the same cell. In previous work these molecules were identified through experiments involving the separation of two kinds of nuclei utilizing differences in the nuclei that may have produced misleading results. In the experiments reported here normal, randomly-chosen ameba (A. proteus) nuclei containing [³²P]RNA were implanted into unlabeled normal, randomly-chosen cells and, after suitable incubation, the labeled RNAs present in each kind of nucleus were characterized by gel electrophoresis. The previously obtained results were confirmed: i.e. (a) the recipient cell nuclei acquired the same four small, distinct RNAs, which are recognized as shuttling ones because they migrate from one nucleus to the other; (b) the grafted nuclei possess, in addition to the four shuttling RNAs, three small, distinct RNAs, which are recognized as non-shuttling RNAs. New evidence also is presented to show that the acquisition by a nucleus of labeled RNAs in the above kind of experiment is not a result of new synthesis of RNAs from the labeled turnover products emanating from the transplanted nucleus.     

Fine structure of the spermatheca of the mealworm beetle (Tenebrio molitor L.)

The spermatheca of the female mealworm beetle is an inflorescence of branching cuticular ducts which is connected to the bursa copulatrix via a cuticular neck surrounded by a muscular coat. The infolded bursal cuticle consists of a distinct outer epicuticle, inner epicuticle, procuticle, and a subcuticular zone; the latter is rich in mucopolysaccharides. The cuticle of the neck lacks a distinct procuticle. The cuticle of the spermatheca itself is mostly inner epicuticle with two thin underlying lamellae of procuticle. The cells of the bursa are loosely coupled to the procuticle, whereas cuticular projections bind the epithelia of the "neck" and the spermatheca proper to the underlying epithelia. The apical plasma membranes of the spermathecal epithelium are sinuous and much infolded; we believe that this epithelium controls the micro-environment within the cuticular ducts.