Sequential Events in the Photoinhibition of Synechocystis under Sodium Stress

Synechocystis (PCC 6714) is photoinhibited at low photon flux density when illuminated in medium devoid of Na(+). Photosynthetic activity and variable fluorescence yield were measured in intact cells during the course of inhibition and during recovery from inhibition in order to characterize sequential inhibitory events. Photosystem II antenna chlorophyll becomes functionally disconnected from the reaction center in the first stage of inhibition, although energy is still transferred from phycobilin pigments to the reaction center. This occurs simultaneously with, or subsequent to, the previously observed (J Zhao, JJ Brand [1988] Arch Biochem Biophys 264: 657-664) inactivation of O(2)-evolution units in Na(+)-stressed cells. Addition of Na(+) to the culture medium rapidly restores the O(2)-evolving system, but reassociation of photosystem II antenna chlorophyll is much slower and requires new protein synthesis. A site nearer to the reaction center of photosystem II becomes inactivated in a secondary inhibitory event. Recovery from secondary inhibition occurs slowly and requires protein synthesis. Cells recovering from secondary inhibition produce active photosystem II units with a fully functional complement of antenna chlorophyll. Synechocystis is photoinhibited in complete (Na(+)-containing) medium when illuminated at high photon flux density. These photoinhibited cells exhibit the same recovery behavior as cells at the second stage of inhibition in Na(+)-deficient medium.

Mitosis-specific monoclonal antibody MPM-2 inhibits Xenopus oocyte maturation and depletes maturation-promoting activity

MPM-2, a monoclonal antibody specific for cells in mitosis, recognizes a family of proteins that share a common phosphorylated epitope. In this study we have shown that during the maturation of Xenopus laevis oocytes induced by progesterone, phosphorylation of MPM-2 antigens coincided with the appearance of MPF activity. When MPM-2 (0.7-1.4 micrograms per oocyte) was injected into oocytes prior to progesterone stimulation, MPF activity failed to appear and induction of maturation was inhibited as judged by both germinal-vesicle breakdown and white-spot formation. Further, MPM-2 was able to neutralize as well as immunodeplete MPF activity from mitotic HeLa cell and mature oocyte extracts. These results suggest that MPM-2 recognizes either MPF itself or a protein(s) that regulates MPF activity and that the kinase that phosphorylates MPM-2 antigens may be a key component in the regulation of M-phase induction.

Intrinsic origin of atrioventricular nodal functional properties in rabbits

The goal of the present study was to document the intrinsic origin of atrioventricular nodal functional properties (recovery time, facilitation, and fatigue) in two groups of six superfused isolated rabbit heart preparations. These properties were determined from recovery curves (A2H2 versus H1A2 intervals) obtained with previously defined periodic premature stimulation sequences performed before and after autonomic blockade demonstrated effective with the injection of agonists. In group 1 preparations, the muscarinic cholinergic and beta-adrenergic receptors were blocked with atropine (1 mg/L) and propranolol (1 mg/L), respectively. The blockade reduced the facilitation and increased the fatigue by the direct membranous effect of propranolol. To avoid this effect in group 2 preparations, propranolol was replaced by sotalol (5 mg/L), which in combination with atropine altered neither the presence nor the magnitude of the functional properties. These results show that the origin of the three nodal functional properties is independent from the autonomic nervous system.

Immunohistochemical dystrophin reaction in synaptic regions

To investigate the functional significance of dystrophin, we studied various tissues of control and mdx mice, and rats immunohistochemically, using anti-dystrophin antibodies. In control animals, we observed the immunohistochemical localization of dystrophin in synaptic regions such as neuromuscular junctions, the cornea and outer plexiform layer of the retina, the taste buds and neurons in the brain, as well as on the surface membrane of skeletal, cardiac and smooth muscle fibers. In mdx mice, dystrophin was absent from the surface membrane of muscle fibers and the outer plexiform layer of the retina. These results suggest that dystrophin plays an important physiological and/or structural role in the conduction system.

Lens-specific expression of recombinant ricin induces developmental defects in the eyes of transgenic mice

An expression system for cell lineage ablation in transgenic mice was constructed in which a modified form of the A subunit of ricin, a toxic lectin produced by the castor bean Ricinus communis, can be expressed under the direction of tissue-specific regulatory signals. A chimeric gene was formed by fusing the promoter and 5'-flanking sequences of the lens-specific mouse alpha A-crystallin gene with a modified ricin A cDNA, and this construction was integrated into the germ line of transgenic mice. These animals develop profound microphthalmia with severe developmental defects of the eye, relating primarily to the disorganization and death of cells forming the lens. In addition, this defect is associated with several abnormalities, including eye size, folding of the retina, and ectopic lens material in other regions of the eye. The phenotype of this engineered developmental mutation suggests that the normal development of alpha A-crystallin-producing lens fiber cells is essential for the proper growth, organization, and orientation of optic structures.

[Extramedullary plasmacytoma of small intestine--a case report]

Extramedullary plasmacytoma (EMP), being different from multiple myeloma, is very rare. One case of primary EMP of small intestine and review of literature are presented. The patient, 69-year-old male, was admitted because of left lower abdominal pain and anemia. A mass, table-tennis in size, was palpated. Intestinal obstruction was found by plain X-ray film. It was diagnosed as EMP of small intestine by pathology after exploratory celiotomy. Immunohistochemical stain showed that intracytoplasmic immunoglobulin was monoclonal IgG. Lambda. The blood Bence-Jones protein and bone marrow puncture were negative. The patient received chemotherapy after operation and was followed for two years giving satisfactory result. The pathogenesis, clinical feature, diagnostic criteria and treatment are discussed.

EEG findings during special psychical state (Qi Gong state) by means of compressed spectral array and topographic mapping

Wallace first reported the changes in EEG during transcendental mediation [6]. Banquet [1] observed, on the basis of spectral analysis of the EEG, that the mediation state was a unique state of consciousness, and separate from wakefulness, drowsiness or sleep. The Qi Gong of China is not the same as either transcendental mediation or the Yoga Gong. The EEG during Qi Gong state is clearly different from those recorded during the resting state. The changes in the EEG during the Qi Gong have not been reported previously. The EEG alpha activity during the Qi Gong state occurs predominantly in the anterior regions. The peak frequency of EEG alpha rhythm is slower than the resting state. The change of EEG during Qi Gong between anterior and posterior half is negative correlation. These changes are statistically significant.

Characterization of rabbit cytochrome P450IIC4 cDNA and induction by phenobarbital of related hepatic mRNA levels

We have cloned cDNA containing a partial sequence of a rabbit cytochrome P-450 (designated cytochrome P450IIC4) cDNA that is a member of the cytochrome P450IIC subfamily. The cDNA contains 770 bp of which the first 429 code for the C-terminal 143 amino acids of cytochrome P450IIC4. The protein coding region of the cDNA is 98% homologous with that of cytochrome P450IIC5 and the 3' untranslated region is about 90% homologous. In contrast to the constitutive isozyme, cytochrome P450IIC5, mRNA in the liver that hybridized to the 3' untranslated region of cytochrome P450IIC4 cDNA was increased about 8-fold 24 hours after a single injection of phenobarbital.

Cosmid vectors for rapid genomic walking, restriction mapping, and gene transfer

We have designed cosmid vectors for rapid genomic "walking" and restriction mapping. These vectors contain the transcription promoters from either bacteriophage SP6, T7, or T3 flanking a unique BamHI cloning site. Mammalian expression modules encoding the dominant marker neomycin phosphotransferase or the amplifiable dihydrofolate reductase gene expressed from SV40 promoters were inserted for use in gene transfer studies. Restriction sites for the enzymes Not I and Sfi I, which cut mammalian DNA very infrequently, have been engineered near the transcriptional promoters to enable the excision of most inserts as single, full-length fragments. Genomic libraries representative of mouse, human, and hamster genomes were constructed by inserting 33- to 44-kilobase-pair (kbp) DNA fragments, generated by partial cleavage of genomic DNA with Mbo I or Sau3A, into the unique BamHI site. Digestion of recombinant cosmids with restriction enzymes that cleave frequently but do not disrupt the transcriptional promoters generates two small DNA templates for the synthesis of end-specific RNA probes to facilitate directional "walking." Cosmid restriction maps can be determined rapidly by one of several methods. The cosmids and methods we describe should have wide utility in determining the functional and structural organization of complex eukaryotic genomes and for physically linking distant genetic loci.

[Cisplatin or combined cisplatin and 60Co radiation in the treatment of advanced lung cancer--report of 145 cases]

The result of 145 patients with advanced primary lung cancer treated by cisplatin alone or combined cisplatin and 60Co radiation from June 1981 to August 1983 is reported. 75 of these cases were clinical stage III and 70 stage IV. 57 (39%) were proved by pathology and 64 (44%) by cytology, totalling 121 (83%) as non-small cell lung cancers. The other 24 (17%) were diagnosed by clinical means. All the patients were divided into two groups. Group I, 26 cases were treated by cisplatin alone. In this group, no complete response was found, the partial response rate was 31% and 1-year survival rate was 40%. Group II, 119 patients were treated by the combination of cisplatin and 60Co radiation. Complete response rate was 16%, partial 59%, 1 and 2-year survival rates were 52% and 33%, respectively. The results show that the combination of cisplatin and 60Co therapy is more effective for the advanced lung cancers.