Female protein (FP), a serum protein present in normal female hamsters was found to be similar to acute-phase reactant, C-reactive protein (CRP) and serum amyloid P component (SAP) in the following ways: (a) hamster FP complexed with phosphorylcholine (PC) in a Ca++-dependent fashion as shown by its isolation from serum by affinity chromatography with PC-Sepharose and selective elution with free PC or EDTA; (b) electron microscopy of FP indicated a pentameric structure similar in size and appearance to other pentraxins; (c) the parent molecule of FP (150,000 mol wt) was composed of five noncovalantly assembled subunits of 30,000 mol wt; and (d) the amino acid analysis and terminal NH2 sequence of FP clearly showed homology with SAP-CRP. Although FP evolved from an ancestral gene common to SAP and CRP, and shares functional, morphological and structural properties with these acute-phase proteins, the biological homology of FP appears quite diverse as this protein is a prominent serum constituent (1-2 mg/ml) of normal female hamsters and under hormonal control (testosterone suppression) in males.

Polypeptin, a basic peptide antibiotic isolated from Bacillus circulans, was separated into two components by countercurrent distribution. The two components, polypeptin A and polypeptin B, had identical amino acid compositions but varied in the structure of the hydroxy acid constituent attached to the alpha-amino group of the peptide chain. Polypeptin A contained 3-hydrosy-4-methylhexanoic acid and polypeptin B contained 3-hydrosy-5-methylhexanoic acid. T-HE STEROCHEMISTRY OF THESE HYDROXY ACIDS WAS NOT DETERMINED. Studies involving partial acid hydrolysis and chemical synthesis are consistent with the lactone sturcture for polypeptin A. Polypeptin B differs only in the position of the methyl group in the hydroxyacyl moiety.

Inbred hamster and mouse cells transformed by the nononcogenic adenovirus (Ad) serotypes, Ad2 and AdS, are nontumorigenic in syngeneic adult animals, while cells from these species transformed by the highly oncogenic Adl2 are tumorigenic in such rodents. By immunoprecipitation and flow cytometry, cells from four of six Ad2-and Ad5-transformed hamster and mouse lines expressed high levels of cell-surface class I major histocompatibility complex (MHC) antigens, while cells from two of these six lines expressed low levels of cell-surface class I MHC antigens. The levels of class I MHC proteins expressed by cells from these latter two lines were comparable to the levels of cell-surface class I MHC proteins expressed by cells from Adl2-transformed hamster and mouse lines. Moreover, an Ad2-transformed line that had become highly oncogenic after in vivo adaptation showed the same high level of MHC expression as the nononcogenic parent. The amounts of class I mRNA, analyzed by RNA blotting, were, in general, consistent with the levels of class I antigens expressed on the surfaces of these cells. These results indicate that there is no correlation between the tumorigenicity in immunocompetent syngeneic adult rodents of Ad2-and Ad5-transformed hamster and mouse cells and the level of class I MHC antigens expressed on the surfaces of these cells. Thus, the expression of different levels of class I MHC proteins does not seem to explain the differences in the oncogenicity between nononcogenic and highly oncogenic human Ad serotypes.Human adenoviruses (Ad) were first shown to be oncogenic in Syrian hamsters by Trentin and coworkers in 1962 (1). Following this discovery, several Ad serotypes were categorized into nononcogenic (Adl, Ad2, Ad5) and highly oncogenic (Adl2, Adl8, Ad3M) groups by their capacity to induce tumors in hamsters and other rodents (2). In spite of the differences in oncogenicity of different Ad

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We previously reported that domestic rabbits of five immunoglobulin K allotype strains (b4', b4, b5, b6, and b9) harbor at least two DNA sequences that hybridize strongly to K constant region probes in Southern blots. One of these sequences ("type A") has been identified as encoding the constant region of the K2 isotype, an immunoglobulin chain that most rabbits express only at low levels, if at all. We identified the second sequence-for rabbits of the b4 allotype-as encoding the nominal b4 K chain (or K1 isotype), but for rabbits of other allotypes no definite identification for this "type B" sequence could be made. Here we suggest that the type B sequence in rabbits of the other domestic allotypes also encodes the nominal K1 immunoglobulin chain. We show this directly for the b5 allotype; a type B sequence cloned from b5 DNA has been found to contain an apparently functional gene encoding the b5 constant region sequence. Indirect arguments suggest the corresponding conclusion for the b'V, b6, and b9 allotypes. We have considered the implications of these results for the phenomenon of "latent allotype" expression.The immunoglobulin K gene system of rabbits is more complex than the well-studied homologous loci of mouse and man in that rabbits demonstrate several allotypic variants of "b series" K chains (known as b4v, b4, b5, b6, and b9 in domestic rabbits) as well as an additional K isotype (known as K2 or "bas") that is generally expressed at very low levels. The inheritance of b series allotype expression is not completely understood (reviewed in ref. 1). Although initial studies indicated that allotypes were controlled by codominantly expressed allelic structural genes, this model was challenged by serologic detection in some rabbits of "latent" allotypes-i.e., K chains unpredicted by pedigree of the rabbits. The phenomenon of latent allotypes suggested that rabbits might harbor structural genes for more K chains than are normally expressed. The usual inheritance of "nominal" allotype expression might then result from an inherited regulatory mechanism that would select the allotype to be expressed; latent allotype expression could result from "leakage" of the regulatory mechanism.We have been pursuing the molecular basis for latent allotype expression by investigating the K chain gene system of rabbits. We recently cloned the nominal b4 germline constant K (CK) gene (designated Klb4) from a b4 rabbit and showed by Southern blot analyses that rabbits of five different b series pedigrees each harbor two sequences strongly homologous to the cloned b4 CK gene (2); the two sequences were arbitrarily designated type A and type B. Subsequent work from our laboratory (3) and from Heidmann and Rougeon (4) identified the type A sequence of a b4 rabbit as encoding the K2 isotype; we refer to this gene as K2b4. By inference, the type A sequences in b4v, b5, b6, and b9 rabbits probably also represent K2 isotype genes.The identity of the type B sequences has been clearly established only in b4 rabbits, where the B...