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Background and aims: Lenvatinib (LEN) is a newly developed tyrosine kinase inhibitor, and is approved as a first-line treatment for advanced hepatocellular carcinoma (HCC) in Japan. This retrospective multi-center study investigated the effect of the relative dose intensity (RDI) of LEN on response rate, progression-free survival (PFS), and overall survival (OS). Methods: This retrospective study enrolled 123 patients with advanced HCC who were treated with LEN at six hospitals in Japan between March 2018 and December 2019. These patients were divided into two groups: RDI ≥70% (RDI 70 group, N = 70) or RDI

Water electrolysis is essential for producing hydrogen as an energy source for society. The development of polymer electrolyte membrane water electrolysis (PEMWE) has also raised the potential for new applications of electrolysis technologies. In this study, we demonstrate deuterium (D) isotope separation where pure water containing heavy water is supplied to the anode of a PEMWE. The D separation was evaluated by measuring the concentration in the drained water and in the generated hydrogen gas. The D separation was measured at several of stoichiometry numbers of feed water, λ, which was ratio of the theoretical water consumption to water feed. Notably, at the same stoichiometry, the D separation depended on the volume of the water feed to the anode of the cell and current density. This effect might be explained by complex water transport behavior governed by electro-osmotic flow and back diffusion across the concentration gradient.

Refractory ascites after liver transplant commonly occurs in living donor liver transplant (LDLT). Refractory ascites is associated with postoperative complications and poor prognosis. This study sought to determine the risk factors of refractory ascites and discuss their perioperative management.A retrospective study of 122 living donor liver transplant recipients between 2008 and 2017 was performed to analyze the risk factors, incidence, and characteristics of refractory ascites. Refractory ascites post LDLT was defined as the production of ascites fluid1000 mL/d on postoperative day 14 or required repeated drainage.A total of 24 patients (19.6%) developed refractory ascites. The 1-year survival rate was significantly worse in the refractory ascites group compared with the nonrefractory ascites group (P .001). In a univariate analysis, patients with refractory ascites had a higher Model for End-Stage Liver Disease (MELD) score, donor age, presence of left lobe graft, ascites at laparotomy, portal venous pressure just after surgery, cold ischemia time, and absence of hepatocellular carcinoma compared with patients without refractory ascites. Multivariate proportional regression analyses revealed that MELD score ≥20, left lobe graft, donor age 50 years or older, and ascites at laparotomy ≥350 mL were independently associated with refractory ascites. Postoperative complications, such as bleeding (P .001), sepsis (P .001), and bloodstream infection within 30 days after LDLT (P .00), were significantly higher in the refractory ascites group.Refractory ascites is associated with reduced 1-year survival and increased postoperative complications. Four factors including MELD score ≥20, donor age 50 years or older, presence of left graft, and ascites at laparotomy ≥350 mL were independent predictors for refractory ascites.

This study investigated Pickering emulsion polymerization of styrene using self-assembled chitin nanofibers (CNFs) as stabilizers to produce CNF-based composite particles, which were further converted into hollow particles. Previously, we reported that regeneration from a chitin/1‑allyl‑3‑methylimidazolium bromide ion gel using methanol fabricated self-assembled CNFs. Prior to the emulsion polymerization, CNFs were maleylated by reaction with maleic anhydride in the presence of perchloric acid. After styrene was added to a dispersion of the produced anionic CNFs in ammonia aq., a mixture was ultorasonicated to give an emulsion, in which styrene droplets were stably surrounded by CNFs. Radical polymerization was then conducted in the presence of potassium persulfate as an initiator to produce the composite particles. Particle sizes became smaller as the amounts of CNFs increased. The hollow particles were prepared by solubilizing out the polystyrene cores with toluene.

2,2′-Bipyridines containing two β-maltoside, β-lactoside, or β-isomaltoside appendages were prepared and successively complexed with ferrous ion to afford hexavalent glycoclusters having tris-bipyridine ferrous complex cores. Each of these metalloglycoclusters showed unique UV–vis and CD spectral changes upon addition of chloride, nitrate, and sulfate salts in carbohydrate- and anion-dependent manners. The results indicate that spatial carbohydrate packing of the metalloglycoclusters changes upon addition of these anions and that different anions stabilize different carbohydrate packings. Furthermore, the sulfates specifically enhance the rheological properties of aqueous solutions containing the metalloglycocluster containing β-lactoside appendages.

Highlights • An enterolith occurring in the duodenal afferent loop after distal gastrectomy, leading to obstructive jaundice and ileus is rare. • Although afferent loop enterolith formation is uncommon, it should be considered when a patient with a history of B-II gastrectomy or Roux-en-Y reconstruction presents with fever, abdominal pain, or other symptoms suggesting acute cholangitis. • Surgical treatment should be considered for afferent loop obstruction or intestinal obstruction that is refractory to conservative treatment., Introduction Afferent loop obstruction is an uncommon complication associated with Billroth II reconstruction or Roux-en-Y reconstruction after gastrectomy. Moreover, cases where the obstruction is caused by enterolith are rare. Here, we report a rare case of afferent loop obstruction caused by an enterolith after Roux-en-Y reconstruction of gastrectomy; subsequently, leading to ileus in the ileum. Presentation of case An 84-year-old man who received a Roux-en-Y distal gastrectomy for gastric cancer presented with symptoms of fever and jaundice 14 months later. Computed tomography (CT) scan revealed an enterolith in the duodenal afferent loop and a dilated intrahepatic bile duct. Although the obstructive jaundice and fever disappeared with conservative therapy, ileus occurred due to the movement of the enterolith into the ileum, which was refractory to conservative therapy. Therefore, enterotomy was performed to remove the enterolith, and the patient had an uneventful recovery. Histologically, the enterolith derived from food residue. No postsurgical sign of recurrence has been noted for 6 months. Conclusion We report a rare case where an enterolith in a duodenal afferent loop after distal gastrectomy led to obstructive jaundice, and subsequently, caused ileus by its movement into the ileum.

Highlights • Appendicitis with liver abscess and sessile serrated adenoma/polyp is rare. • Ileocecal resection was performed for an inflammatory mass in the ileocecum. • The patient was successfully treated with a combination of surgery and antibiotics., Introduction Although appendicitis is a common disease, appendicitis concurrent with liver abscesses and sessile serrated adenoma/polyp (SSA/P) is rare. Presentation of case A 69-year-old man presented with symptoms of abdominal pain and fever. Computed tomography (CT) revealed multiple liver abscesses and an enlarged appendix with a pseudotumoral appearance, which suggested acute appendicitis. In the emergency operation, ileocecal resection was performed for the perforated appendicitis with an inflammatory mass in the ileocecum. On macroscopic examination, the torose lesion was localized at next to the appendiceal orifice. The tumor was diagnosed as SSA/P based on the microscopic finding. The postoperative course was uneventful, and the liver abscesses were cured by antibiotic therapy. The patient was discharged 17 days after the surgery. Discussion In this case, SSA/P localization at next to the appendiceal orifice was suggested as the cause of the perforated appendicitis with multiple liver abscesses. The patient was successfully treated with a combination of surgery and antibiotic therapy. Conclusion This is the first reported case of a patient with SSA/P that led to acute appendicitis with multiple pyogenic liver abscesses.

In this study, the seasonal variation of geo-environmental condition of Yamaguchi Bay tidal flat has been studied. Yamaguchi bay is located at the south part of Yamaguchi prefecture and was famous for its different kind of shells and other living creatures. However, a sharp declination of a catch of shells and crabs have been observed in recent years. Particularly, the living creatures related to the tidal flat mud have been suffered a damage. Recently, the horseshoe crabs which used to come onto shore to mate is declining in Yamaguchi bay which is not good for the marine ecosystem of this area. The mud samples were collected from the tidal flat area once in every month by using the tube sampler. Then the samples were cut into specified layer and measured the different geo-environmental parameters (acid volatile sulfide, pH, loss on ignition, COD, Electrical conductivity) at the laboratory in each layer. It was observed that the acid volatile sulfide (AVS) which is the most important parameter for the living condition of the living creatures is over the safe limit (0.2 mg/g-dry mud) during the summer. The other parameters such as pH, LOI, have also significant variation in different seasons but they were still within the safe limit. The COD value of the tidal mud also showed a significant variation during the summer and the winter. However, the higher AVS value was one of the reasons for the declination of horseshoe crabs and other living creature in the tidal flat of Yamaguchi bay, Japan.

Highlights • Completely different types of GIST rupture have been reported as same perforation type. • We classified retrieved cases of GIST rupture to three types: abscess type, hemoperitoneum type, bowel perforation type. • Each type demonstrates a specific mechanism of perforation causing characteristic complaints., Introduction Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract. Overt peritonitis caused by GIST rupture is very uncommon. Three types of GIST rupture have been described: closed perforation due to abscess (abscess type), hemoperitoneum leading to rupture of the hematoma capsule in the tumor (hemoperitoneum type), and perforation of the digestive tract via a fistula leading to central necrosis of the tumor (bowel perforation type). This report describes a patient with spontaneous tumor rupture and diffuse peritonitis, a variant of the bowel perforation type of GIST rupture. Presentation of case A 74-year-old man presented with symptoms of vomiting and abdominal pain. Computed tomography (CT) scan revealed an approximately 10 × 7-cm mass in the pelvis with free air and fluid collection. Emergency laparotomy revealed a tumor in the jejunum, which was ruptured with a hole measuring 5 mm in diameter. The tumor and part of the jejunum were resected. Immunohistochemically, the mass was diagnosed as a GIST originating from the gastrointestinal tract. Despite chemotherapy with imatinib mesylate, the patient died 22 months after surgery. Conclusions This report describes a patient with acute diffuse peritonitis due to spontaneous rupture of a primary GIST of the jejunum.

Quantum dot sensitized solar cells (QDSSCs) have attracted much interest due to their theoretical efficiency, predicted to be as high as 44%. However, the energy conversion efficiency of QDSSCs is still a lot lower than the theoretical value, one reason for which is the number of surface defects on the QDs. In order to improve the conversion efficiency, surface passivation of the QDs has been applied to QDSSCs. Studying the mechanism of how the surface passivation influences the photoexcited carrier dynamics is very important. In this paper, we clarify the effects of CdS passivation on electron injection, trapping and recombination in CdS passivated PbS QDSSCs (called PbS/CdS double-layered QDSSCs). We found that electron trapping and recombination can be suppressed effectively, and that the electron injection efficiency can be increased significantly by surface passivation with CdS on PbS QDSSCs. Our findings provide a better understanding of the effects of surface passivation on QDSSCs, which will prove beneficial for making further improvements in the photovoltaic properties of QDSSCs.

To understand the high affinity and specificity of an RNA aptamer against Fc region of human immunoglobulin G1 (hFc1), we analyzed the binding profiles of the RNA aptamer-hFc1 complex by studying its interaction using ab initio fragment molecular orbital calculations. Our calculations revealed that base-flipped G7 nucleotide is critical for hFc1 binding due to its robust interaction energy with hFc1 in the phosphate and base groups. It was suggested that G7 nucleotide renders a high degree of shape complementarity with the hFc1 molecule surface. This study provides physicochemical insights into the binding of the RNA aptamer to hFc1.

The number of bedridden elderly patients who need a liquid diet has been increasing. We evaluated the usefulness of a tube-fed liquid diet containing cellulose and oligosaccharide for elderly bedridden patients.Twenty-two elderly bedridden patients were given a liquid diet containing cellulose and lafinose for 4 wk. Parameters associated with blood and stool weight were measured during this period.Stool weight increased by 32.0 g in men and 8.8 g in women at 2 wk and remained at these weights up to 4 wk (P0.05 before and after 2 wk, 3 wk, and 4 wk in men, and P0.05 before and after 3 wk in women). Body weight increased in men (0.5 kg) and women (0.7 kg) 15 d after starting the diet and then remained at these values up to 29 d thereafter, and statistically significant differences were not seen. There were no changes in nutritional parameters such as total protein.No significant changes were observed in the general condition of elderly patients, with the exception of a positive increase in fecal weight, by 30-d supplementation of a liquid diet containing cellulose and lafinose.

An ionizing radiation-sensitive mutant derivative of mouse lymphoma L5178Y cell, M10, is defective in rejoining DNA double-strand breaks (DSBs). The complementation test and the results of chromosome transfer suggested that M10 may belong to X-ray cross-complementation (XRCC) group 4. In the present study, sequence analysis of Xrcc4 cDNA in M10 cells disclosed a transversion of A (370) to T, which result in a change of arginine (124) to a termination codon. Interestingly, the mutation occurred in one allele and the transcripts of the Xrcc4 gene were expressed exclusively from the mutant allele. Transfection of M10 cells with the murine Xrcc4 cDNA completely rescued X-ray sensitivity of the mutant cells. M10 is a novel Xrcc-4-deficient cell line.

We established the radiosensitive cell line SX9 from mammary carcinoma cell line FM3A. In SX9 cells a defect of DNA-dependent protein kinase (DNA-PK) activity was suggested. Additionally, a complementation test suggested that the SX9 cell line belongs to a x-ray cross-complementing group (XRCC) 7. Isolation and sequence analyses of DNA-dependent protein kinase catalytic subunit (dna-pkcs) cDNA in SX9 cells disclosed nucleotide “T” (9572) to “C” transition causing substitution of amino acid residue leucine (3191) to proline. Interestingly, the mutation occurs in one allele, and transcripts of the dna-pkcs expressed exclusively from mutated allele. V(D)J recombination assay using extrachromosomal vector revealed the defects of not only coding but also signal joint formation. The frequency of the signal joint decreased to approximately one-tenth and the fidelity drastically decreased to 12.2% as compared with the normal cell line. To confirm the responsibility of thedna-pkcs gene for abnormal V(D)J recombination in SX9, the full-length dna-pkcs gene was introduced into SX9. As a result, restoration of V(D)J recombination by wild typedna-pkcs cDNA was observed. SX9 is a noveldna-pkcs-deficient cell line.

The biological effects of active oxygen species were examined in a mutant mouse cell line (SL3-147) that is deficient in the repair of DNA double-strand breaks. This mutant cell line shows different sensitivities to X-rays, hydrogen peroxide, paraquat and menadione when compared to the wild-type cell line (LTA). SL3-147 was more sensitive to X-rays, hydrogen peroxide and paraquat, but was less sensitive to menadione in side by side comparisons to LTA cells. The greater number of DNA double-strand breaks in SL3-147 appears to account for the line's greater sensitivity to X-rays and paraquat. DNA damage other than double-strand breaks or injury to non-DNA targets, however, is responsible for the differences between LTA and SL3-147 in their sensitivities to hydrogen peroxide and menadione.

The mouse lymphoma (L5178Y) cell mutant M10 is defective in rejoining DNA double-strand breaks and is hypersensitive to ionizing radiation. The introduction of human chromosome 5 into M10 cells by microcell mediated chromosome transfer complemented the ionizing-radiation hypersensitivity defect of this cell line. The presence of chromosome 5 in the microcell hybrids was shown using PCR with chromosome-specific primers and fluorescence in situ hybridization. From this data we conclude that the gene that corrects the radiation hypersensitivity of M10 cells is located on chromosome 5 and tentatively assigned to the 5q14 to 5pter region. We designate this gene XRCC4L.

The mutant mouse lymphoma cell Q31, which is sensitive to 4-nitroquinoline 1-oxide and ultraviolet radiation (UV), was compared with the parental L5178Y cell for the effect of caffeine and mutation induction after UV irradiation. Caffeine potentiated the lethal effect of UV in both cell strains to a similar extent, indicating that the defective process in Q31 cells was caffeine-insensitive. UV-induced mutation to 6-thioguanine resistance was determined in L5178Y and Q31 cells. The maximal yield of mutants was obatained 7 days post-irradiation in L5178Y cells and 14 days in Q31 cells for higher UV doses. It appears that a much longer time is required for the mutant cells than for the parental cells for full expression of the resistance phenotype even at equitoxic UV doses. A substantially higher frequency in induced mutations was observed in Q31 cells than in L5178Y cells at a given dose of UV. A plot of induced mutation frequency as a function of logarithm of surviving fraction again indicates hypermutability of Q31 cells as compared with the parental strain. In contrast, X-rays induced a similar frequency of mutations to 6-thioguanine resistance in L5178Y and Q31 cells.

The mutant mouse lymphoma cell M10, which is sensitive to methyl methanesulfonate and ionizing radiation, was compared with the parental L5178Y cells for mutation induction after γ-irradiation. The rate of induced mutations to 6-thioganine resistance in L5178Y cells was 2−3 x 10 −7 per R, as determined after exposure ranging from 25 to 500 R. The induced mutation frequency per unit dose per locus in M10 cells was about 4 times higher than that in L5178Y cels at the lower doses of exposure (25–75 R), but it declined sharply at the higher doses of γ-rays (100–150 R). The rate of induced mutation per unit cell killing in M10 cells was nearly the same as that in L5178Y cells when they were compared at the levels of lower cell killing.

Three mutagen-sensitive mutants, MS-1, M10 and Q31, have been isolated from mouse L5178Y cells. MS-1 cells are sensitive to methyl methanesulfonate (MMS), M10 cells are cross-sensitive to X-rays, MMS and 4-nitroquinoline 1-oxide (4NQO), and Q31 cells are cross-sensitive to UV and 4NQO. Lines resistant to 6-thioguanine (TGr) and 5-bromo-2′-deoxyuridine (BUr) were isolated from L5178Y and these three mutagen-sensitive mutants. All the TGr lines were sensitive to 5-bromo-2′-deoxyuridine and HAT medium and all the BUr lines were sensitive to 6-thioguanine and HAT medium. The hybrids homozygous for the mutagen-sensitive markers showed nearly the same sensitivity to UV, 4NQO, X-rays and MMS as their parental TGr and BUr lines. The hybrids constructed by fusing L5178Y BUr and TGr lines from each of MS-1, M10 and Q31 displayed the normal UV, X-ray and MMS resistancy of L5178Y cells. Thus the UV-, X-ray- and MMS-sensitive markers in MS-1, M10 and Q31 were recessive in somatic cell hybrids. The 4NQO-sensitive phenotype, however, behaved codominantly in somatic cell hybrids.

Three X-ray-sensitive mutants (LX821, LX827 and LX830) have been isolated from mouse-lymphoma L5178Y cells. These mutants are much more sensitive to the lethal effects of ionizing radiation than the parental L5178Y cells but are as resistant to ultraviolet radiation as L5178Y cells. We have previously isolated a mutant M10 that is sensitive to methyl methanesulfonate (MMS) and cross sensitive to ionizing radiation and 4-nitroquinoline 1-oxide (4NQO). Unlike M10 cells, newly isolated mutants were not sensitive to MMS and were less sensitive to 4NQO. These results indicate that new mutants may be deficient in the repair of DNA damage specific to ionizing radiation. LX821 and LX827 cells were concomitantly resistant to 5-bromodeoxyuridine, whereas LX830 cells were not.

2 mutant mouse cells M10 and Q31 were examined for chromosomal aberrations induced by ultraviolet radiation (UV) and 4-nitroquinoline-1-oxide (4NQO), as compared with mouse lymphoma L5178Y cells. Q31 cells are UV- and 4NQO-sensitive cells isolated from L5178Y cells. M10 cells are similar but are sensitive to ionizing radiation and 4NQO. After treatment with UV or 4NQO, chromatid-type aberrations in these cell strains were induced more frequently in the first mitotic cells, at late fixation times. After UV exposure (2.4 J./m2), the maximal frequencies of chromatid-type breaks in Q31 cells were about 5 times higher than in L5178Y cells. In M10 cells such breaks were only as frequent as in L5178Y cells. After 4NQO treatment (50 ng/ml) the frequencies of chromatid-type breaks in M10 and Q31 cells were significantly higher than in L5178Y cells. From these results and those of previous studies (Takahashi et al., 1982), M10 cells may be considered hypersensitive to γ-rays and 4NQO, but not to UV, and thus react similarly to L5178Y cells. The hypersensitivity of M10 cells to 4NQO may result from a defect in the ionizing-radiation repair mechanism as has been suggested to occur in ataxia telangiectasia (AT) cells. Q31 cells are hypersensitive to UV and 4NQO, but not to γ-rays. Q31 cells may be considered to be deficient in a UV-like repair pathway. In conclusion, characteristics of murine M10 and Q31 cells are compared with those of human AT and xeroderma pigmentosum (XP) cells.

Mouse cells in culture are inefficient in excision of pyrimidine dimers induced by ultraviolet irradiation (UV) (Lehmann and Kirk-Bell, 1972). Despite this inefficiency, mouse cells are as resistant to the lethal effects of UV as are excisionproficient human cells (Rauth et al., 1974; Sato and Setlow, 1981). The mechanism of tolerance by which mouse cells survive UV irradiation is not clear. UV-sensitive mouse cell mutants, if isolated, would be useful for the study of this mechanism. We have isolated a UV-sensitive mutant, Q31, from mouse lymphoma L5178Y cells (Sato and Hieda, 1979), and this mutant has been examined for excision and postreplication repairs of UV damage (Sato and Setlow, 1981). The results show that the parental mouse cells remove 10-20% of induced dimers during the 24-h incubation period and that Q31 cells cannot remove detectable amounts of dimers. Hence the lack of excision repair may be to some extent responsible for the elevated UV sensitivity in mutant cells. Post-replication repair, which will represent another tolerance mechanism operative in mouse cells, was examined to find out whether this mechanism is missing from mutant Q31 cells; the increase in molecular weights of newly synthesized DNA after irradiation was compared between mutant and parental cells, The size of DNA synthesized immediately after irradiation was smaller in mutant than in parental cells, but the rate of DNA-chain elongation was not much different between mutant and parental cells (Sato and Setlow, 1981). However, the changes in the rates of DNA synthesis during the post-irradiation incubation period have not been determined yet. For this report we measured the rates of DNA synthesis after irradiation and observed an affected recovery of UV-inhibited DNA synthesis in mutant cells.

The radiation-sensitive mutant M10 of mouse lymphoma L5178Y cells was examined for its ability to rejoin DNA single-strand breaks induced by gamma-rays. The alkaline sucrose gradient sedimentation analysis revealed that M10 cells repaired single-strand breaks but simultaneously produced increasing amounts of small DNA fragments with time of postirradiation incubation, something which was not observed in L5178Y cells. Since small fragments did not appear in M10 cells irradiated at room temperature, DNA fragmentation may result from cold treatment during irradiation followed by incubation at 37 degrees C. This indicates that the cold susceptibility is characteristic of M10 cells and is not related to radiation sensitivity of this mutant. This conclusion is supported by the finding that no DNA degradation takes place after cold treatment with a subsequent incubation in the other radiosensitive mutant LX830 that belongs to the same complementation group as M10.

In order to establish a simple and efficient method of electroporation applicable to gene transfer in mammalian cells, the effects of various pulsing conditions on viability and transformation efficiency were studied. By investigating the effects of temperature during and after the pulse, field strength, pulse length, and pulsing media, we have established a standard method: a single decaying pulse with a duration of around 1 ms at room temperature in a medium containing physiological concentrations of salts, including Ca2+ and Mg2+. Application of the standard method to various types of cells, both floating and adherent, resulted in an efficient transformation by pSV2neo DNA. Furthermore, the electroporation-mediated transformation of tsBN2 cells by a cosmid clone (∼ 45 kb) carrying the human gene RCC1 was successful.

About fifty suppressor sensitive (sus) mutants of phage ∅80 were isolated after hydroxylamine treatment, and these were classified into fourteen cistrons. In vitro and in vivo complementation experiments revealed that at least five cistrons were concerned with head formation and that at least six cistrons were concerned with tail formation in ∅80. Some presumed “early” mutants were also found. Defective lysogens were isolated from a ∅80-lysogenic nonpermissive strain using the colicin plate method (Gratia, 1966). In these strains deletions which affected the colicin B receptor gene extended for varying distances into prophage ∅80. Marker rescue experiments were carried out with these deletion lysogens by infecting various sus mutants, and the gene order in prophage ∅80 was determined. Clustering of all head genes and also of tail genes, as in phage λ, were demonstrated by the results of the prophage deletion mapping as well as the two-factor crosses performed among the sus mutants. Moreover, the gross gene arrangement of ∅80 was also similar to that of phage λ: namely, the cluster of head genes was found to be located at one end of the vegetative map of ∅80, being followed by that of tail genes, and presumed “early” genes are located at the other end of the map.

φ80 DNA prepared by a mild phenol extraction method had a buoyant density in a CsCl gradient of 1.710 g cm−3 and a thermal denaturation temperature of 90.5°. The buoyant density and thermal denaturation temperature of φ80pt1 DNA were identical to those of φ80 DNA. φ80 DNA had a guanine plus cytosine content of 53 mole per cent which was slightly higher than that of λ DNA or Escherichia coli DNA. The molecular weight of φ80 DNA estimated from the sedimentation rate was 29.3 × 106, and that of φ80pt1 DNA was 31.0 × 106. The significance of the observed difference in molecular weight between φ80 DNA and φ80pt1 is discussed.

Transducing variants of coliphage λ have been isolated from a donor strain in which the normal prophage-host relationship is altered by a deletion that extends from the galE gene of the host into the Q gene of the prophage. The 40 λ gal strains isolated fall into 8 classes. Two classes do not carry the deletion of the donor strain and must have arisen in the primary recipient. The most common class contains phage genes SR A-J and part of gene Q, and might arise by cutting at the att site. One class of λ gal contain all known λ genes except for a large section of gene Q. Lysogens of this class lyse late after induction, liberating a small amount of phage. A further mutation ( qin ) allows plaque formation by these Q-deletion phages, apparently by shortening the latent period. The qin mutation entails a physical loss of DNA, genetic loss of the gal genes and a loss of ability to complement genes S and R in trans .

Mutations in the anthranilate synthetase eistron can alter the capacity to synthesize other enzymes of the tryptophan pathway in Escherichia coli. On the other hand, a deletion over the anthranilate synthetase eistron leads to non-repressible transcription of tryptophan genes. From this evidence it is concluded that the operator should be localized at the anthranilate synthetase eistron extremity of the operon.

Specific tryptophan messenger RNA molecules synthesized at an early stage of de-repression in Escherichia coli were analysed by sucrose density-gradient sedimentation. In these experiments, the following results were obtained: (a) on the tryptophan operon, macromessenger RNA molecules of sedimentation coefficient about 33 s were synthesized; (b) the messenger RNA molecules made from mutants in which only anthranilie acid synthetase (anth) cistron or nearly half the tryptophan operon of the A cistron side is preserved were smaller in size than those from the intact tryptophan operon; (c) the synthesis of the messenger RNA on the tryptophan operon was initiated at the beginning of the anth cistron (operator) and proceeded to the end of the A cistron. Following the progress of synthesis, the messenger RNA grew in molecular size. In the wild type strain W3102, anth messenger RNA only existed as an initial and incomplete product among the tryptophan messenger RNA; (d) upon repression, the tryptophan repressor blocked the initiation of specific messenger RNA synthesis by associating with the operator site. The synthesis of the messenger, once initiated from the operator, is not brought to a halt immediately by tryptophan repression, but probably proceeds to the other end of the operon. In short, it is concluded that tryptophan messenger RNA molecules are multicistronic; the so-called operator to which the tryptophan repressor has an affinity, is located on the anth cistron side, and is the initiation site for the synthesis of the tryptophan messenger RNA molecules.

Messenger RNA was detected which formed a specific hybrid with DNA of the tryptophan region carried by bacteriophage φ80. Since the synthesis of specific messenger RNA corresponds to the genetic properties and physiological activities of the tryptophan genes in Escherichia coli cells, messenger RNA is considered to be specifically related to the genetic information of the tryptophan synthesizing system. Through the hybridization technique with DNA's from φ80 dt 0 which carries the entire region of the tryptophan system, and φ80 pt 1 which carries the tryptophan region with a deletion of the anthranilic acid synthetase cistron, a specific messenger RNA corresponding to the anthranilic acid synthetase cistron was detected. Because the rate of synthesis of specific tryptophan messenger RNA was reduced by the addition of tryptophan, it is concluded that regulation in the tryptophan system operates at the gene level.

The density of bacteriophage φ80 was measured by density gradient equilibrium centrifugation in CsCI solutions. This density was the same in phages derived from a lysogenic or a lytic growth cycle. The distribution of low-frequency transducing (LFT) particles of φ80 in a CsCl density gradient was shown to be much broader than that of plaque-forming particles. The transducing phages in the LFT lysates appear to transmit their characteristic densities, as well as definite try markers, to the φ80 dt particles in the high-frequency transducing lysates derived from them. The φ80 dt particles can be divided into two classes according to their requirement for helper phages in transduction. One class transduces more efficiently in the presence of active helper phage, while with the other class the active phage does not enhance or even reduces the transduction frequency. A new transducing phage type, which is not defective since it multiplies without help from the active phage, has been isolated. This phage, called φ80 pt (plaque-forming tryptophan), forms a small turbid plaque. A tryptophan auxotroph lysogenized by φ80 pt becomes try+, although it always segregates out some try− nonlysogenic cells. The buoyant density of φ80 pt in CsCI solution is greater than that of φ80, suggesting that a larger genetic fragment is carried in this phage.

A temperature-sensitive mutant (ts 39) of murine leukemic cells was shown to undergo micronucleation upon exposure to the non-permissive temperature. The formation of micronucleate cells appeared to be preceded by an increase in the fraction of mitotic cells. Since this phenomenon resembles micronucleation induced by colcemid, it is possible that ts 39 cells may be defective in microtubule assembly.