RNA metabolism in apices of Pharbitis nil daring floral induction

RNA metabolism was studied in apices of Pharbitis nil duringand after floral induction. In continuous light ³H-uridine accumulatedin RNA at a constant rate over an 18 hr period. In darkness,however, the rate of accumulation of label into RNA was constantuntil the 10th hour at which time a rapid burst of accumulationoccurred, peaking at the 14th hour of darkness and followedby a net loss of label. The RNA involved in this burst is probablymRNA due to its size and poly(A) content. This phenomenon doesnot seem to be associated with floral induction, since the siteof perception is the apex, and it also occurs under conditionswhere floral initiation is inhibited by a brief light interruptionof the dark period. Immediately after floral induction by a16-hr dark period the rate of RNA synthesis was suppressed about14%. This suppression lasts for about 12 hr and was followedby a twofold increase in the rate of RNA synthesis, comparedto non-induced apices, at 64 hr after the beginning of the inductivedark period. These post-induction changes were found to occurin all RNA fractions. ¹Present address: Department of Radiation Biology and Biophysics,University of Rochester School of Medicine and Dentistry, Rochester,N.Y. 14642, U.S.A. (Received March 15, 1976; )     

Qualitative analysis by isoelectric focusing of the protein content of Pharbitis nil apices and cotyledons during floral induction

The protein content of apices and cotyledons in Morally inducedor vegetative plants of Pharbitis nilwas examined using isoelectricfocusing. No differences were found in the protein patternsproduced by apical tissue with and without floral induction.Cotyledons, however, repeatedly showed the distinct loss ofa single protein band on floral induction. ¹Current address: Department of Radiation Biology and Biophysics,The University of Rochester School of Medicine and Dentristry,Rochester, N.Y. 14642, U.S.A. (Received March 29, 1976; )     

Tuberculous Enteritis

Tuberculous enteritis occurs in about 2 percent of patients with pulmonary tuberculosis. Although it is uncommon in the United States, tuberculous enteritis should be considered in any patient with active pulmonary tuberculosis and abdominal complaints.Eight cases of T. enteritis have been treated at Harbor General Hospital in the last 25 years. Associated pulmonary disease was shown radiologically to be present in seven of eight patients. Findings on contrast studies of the gastrointestinal tract showed disease in six of six patients examined.In five patients, surgical operation was required for diagnosis or complications. Resection of diseased bowel with primary anastomosis was done in five patients. Although medical therapy is the mainstay in the treatment of both pulmonary and intestinal tuberculosis, one staged resection of diseased bowel with primary anastomosis is the procedure of choice for complications such as obstruction, hemorrhage or perforation.     

A radioimmunoassay for the Gm(b0) allotype of human immunoglobulins

A radioimmunoassay for the human allotype Gm(b⁰) which provides a sensitive and quantitative measurement of the level of this IgG3 genetic marker has been developed. The assay system can detect 15 nanograms of Gm(b⁰) IgG3 protein and is not inhibited by immunoglobulins of other allotypes and isotypes. Using this assay, good correlation was found between IgG3 and Gm(b⁰) levels in homozygous Gm(f, b⁰) sera and gene dosage effects could be confirmed. The correlation between Gm(b⁰) levels and IgG3 in Negroid Gm(a, b⁰) sera was not as good. This reduced correlation has been attributed to antigen differences in the IgG3 Gm markers characteristic of some Negroid Gm(a, b⁰) sera.     

Expression of the H-Y Antigen on thymus cells and skin: Differential genetic control linked toK end ofH-2

The strength of the H-Y antigen on thymus cells and on skin was compared in differentH-2-congenic mouse strains using a host-versus-graft reaction popliteal lymph node assay, and skin grafts from males of parental strains grafted to F₁ hybrid females. The results revealed considerable differences in the strength of the H-Y antigen among different congenic strains; these differences demonstrate the effect of theH-2-linked gene on the expression of the H-Y antigen. The linkage withH-2 was also confirmed in tests with segregating F₂ generations. In the strains bearing recombinantH-2 haplotypes, the strength of the H-Y antigen is similar to that of parental strain from which the recombinant received itsK end, and the responsible gene (or genes) map to the left ofI-C. The effect of theH-2-linked gene(s) on thymus cells and skin is different. The gene linked to theK end ofH- 2^b determines a strong H-Y antigen on thymus cells, but a relatively weak H-Y antigen on skin. The gene linked to theK end ofH- 2^k determines a weak H-Y antigen on thymus cells, but a strong H-Y antigen on skin. The gene linked to theK end ofH- 2^d determines a weak H-Y antigen on both thymus cells and skin. Our observations raise the possibility that the structural gene for the H-Y antigen is linked toH-2. Alternative (but not exclusive) explanations invoke regulatory effects ofH-2 on the expression of the H-Y antigen, possibly by means of the control of the cellular andogen receptors.     

Reactions of plastocyanin and cytochrome 553 with Photosystem I of Scenedesmus

Chloroplast material active in photosynthetic electron transport has been isolated from Scenedesmus acutus (strain 270/3a). During homogenization, part of cytochrome 553 was solubilized, and part of it remained firmly bound to the membrane. A direct correlation between membrane cytochrome 553 and electron transport rates could not be found. Sonification removes plastocyanin, but leaves bound cytochrome 553 in the membrane. Photooxidation of the latter is dependent on added plastocyanin. In contrast to higher plant chloroplasts, added soluble cytochrome 553 was photooxidized by 707 nm light without plastocyanin present. Reduced plastocyanin or cytochrome 553 stimulated electron transport by Photosystem I when supplied together or separately. These reactions and cytochrome 553 photooxidation were not sensitive to preincubation of chloroplasts with KCN, indicating that both redox proteins can donate their electrons directly to the Photosystem I reaction center. Scenedesmus cytochrome 553 was about as active as plastocyanin from the same alga, whereas the corresponding protein from the alga Bumilleriopsis was without effect on electron transport rates.

It is suggested that besides the reaction sequence cytochrome 553 → plastocyanin → Photosystem I reaction center, a second pathway cytochrome 553 → Photosystem I reaction center may operate additionally.     

E rosette formation at 37°:A property of mitogen-stimulated human peripheral blood lymphocytes

Peripheral blood lymphocytes from healthy humans formed stable E rosettes with sheep erythrocytes (SRBC) at 37°C after culture with phytohemagglutinin or the divalent cation ionophore A23187. Cells manifesting this phenomenon exhibited “blast” morphology, appeared by 16 hr of culture, increased dramatically in percentage and absolute number by 62 hr, and persisted in large numbers for the duration of culture (182 hr). Unstimulated lymphocytes formed rosettes at 4°C but not at 37°C. Increased “stickiness” due to surface-bound lectin mitogen was not the cause of rosette formation at 37°C.Formation of E rosettes at 37°C has previously been considered a property of lymphocytes less differentiated than the circulating T cell (e.g., thymocytes, leukemic lymphoblasts). The present findings indicate that this property can be “reexpressed” during blastogenesis in culture.This observation also demonstrates technical problems associated with the use of SRBC to quantitate lymphocytes with complement receptors (B cells) by the EAC rosette assay in culture. False positives resulted from 37°C E rosette formation, but this was overcome by replacing the SRBC with guinea pig erythrocytes in the EAC assay.