Transformation of cucumber (Cucumis sativus L.) plants using Agrobacterium tumefaciens and regeneration from hypocotyl explants

Summary Transgenic cucumber (Cucumis sativus L.) plants were successfully obtained from hypocotyl explants inoculated with Agrobacterium tumefaciens, which harbored a binary vector plasmid with NOS-nptII, CaMV 35S-I-gus and CaMV 35S-hph genes. Acetosyringone enhanced the efficiency of transformation at the cut surface cells of hypocotyl explants during five days of co-cultivation. Transformed cells were more effectively selected using 20–30 mg/l hygromycin B than using 50–100 mg/l kanamycin. Shoot regeneration occurred within 4–6 wks, and 12 of 21 regenerated plantlets displayed strong GUS expression in the very young leaves. All of 8 GUS-positive R0 plants examined showed single or a few positive bands by Southern blot analysis. The expression of the CaMV 35S-I-gus gene was observed in various tissues and organs of R0 and R1 transgenic cucumber plants.     

Accumulation of multiacetylated forms of histones by trichostatin A and its developmental consequences in early starfish embryos

Summary External application of 10 rig/ml (R)-trichostatin A (TSA), a potent and specific inhibitor of mammalian histone deacetylase, to the embryo of the starfish Asterina pectinifera inhibited development during the early gastrula stage before formation of mesenchyme cells. The TSA-sensitive period was limited to the mid-blastula stage before hatching. The pulse-chase experiment clearly demonstrated that TSA induced an accumulation of acetylated histone species in blastulae through inhibition of historic deacetylation. Similar blockage of development at the early gastrula stage was observed with n-butyrate, which has been known as a weak inhibitor of historic deacetylase. These results suggest an intimate role for historic acetylation-deacetylation equilibria in starfish development. Correspondence to: S. Ikegami     

Strain differences to effects of aging on concentrations of amino acids in cerebrospinal fluid between Sprague Dawley rat and Wistar Kyoto rat.

Age-related alterations and differences of weights and those of amino acid concentrations in the cerebrospinal fluid (CSF) were evaluated between Sprague Dawley (SD) rats and Wistar Kyoto (WKY) rats from eight to twenty weeks of age. The weights of SD rats were heavier than WKY rats at all ages. The age-related alterations of the CSF concentration of many amino acids within each strain were significant but showed no significant trend with age. Between the strains, the concentration differences of excitatory and inhibitory amino acids were not frequent although the concentrations of arginine, alanine and threonine were significantly higher in SD rats than in WKY rats. These results suggest that the different CSF concentrations of amino acids may relate to characteristics of rat strains.     

Simple and rapid quantitative assay of C-labelled urea in human serum using liquid chromatography-atmospheric pressure chemical ionization mass spectrometry

A simple and rapid quantitative method for ¹³C-labelled urea ([¹³C]urea) in human serum was developed by using high-performance liquid chromatography-atmospheric pressure chemical ionization mass spectrometry (HPLC-APCI-MS). This method is used to establish and normalize the [¹³C]urea breath test, which is considered as an effective diagnostic method for Helicobacter pylori infection. HPLC-APCI-MS, involving a simple pretreatment process such as diluting serum with water, was shown to be able to discriminate the extrinsic [¹³C]urea from intrinsic urea present at high concentration in serum. In addition, a ¹³C nuclear magnetic resonance spectroscopic quantitative method for [¹³C]urea in human urine is also described. The precision and accuracy of measured concentrations in these two methods were found to be within the acceptable limit. An application of these methods to investigate the pharmacokinetic profile of orally administered [¹³C]urea in human serum and urine is also presented.     

Further studies on potassium uptake rhythm in the long-day duckweed Lemna gibba G3 with special reference to vegetative growth

Some properties of the circadian rhythm in potassium uptakeof flow medium culture of the long-day duckweed Lemna gibbaG3 were examined.

1. In total darkness, the rhythm faded out in ca. 48 hr; it restartedon transfer to continuous light. Under low-intensity light (below700 lux), the rhythm was damped rapidly
2. The rhythm appearedregardless of the potassium concentrationin the culture medium(from 10/m to 2 HIM). The amplitude, butnot the period, ofthe rhythm was influenced by the ambientpotassium concentration.
3. Alteration in the light intensity or medium composition causeda change in the growth rate without modifying the period ofthe rhythm.
4. These results indicate that potassium uptake rhythmin thisduckweed is typical light-on rhythm, which has no directrelationwith the rate of vegetative growth and requires lightenergyfor its duration.

¹Present address: Aichi-Gakuin University, Chikusa-ku, Nagoya464, Japan. ²Present address: National Institute for Basic Biology, Okazaki,Aichi 444, Japan. (Received February 1, 1979; )     

Rhythm in potassium uptake by a duckweed, Lemna gibba G3

The potassium uptake activity of the "flow-medium culture" ofa long-day duckweed, Lemna gibba G3, followed a circadian rhythmwhich persisted for more than 5 days under continuous light.The period of the rhythm was about 25 hr under 3000 lux at 26?Cand was slightly over-compensated against temperature, Q₁₀ beinga little less than 1.0. The amplitude of the rhythm was dependenton light intensity, and there was no potassium uptake in thedark. Magnesium uptake was affected by the potassium movementand showed circadian rhythmicity with a small amplitude underconditions where the potassium uptake was already saturated.Calcium uptake did not show any obvious rhythm. In Contrastto L. gibba, a short-day duckweed L. perpusilla 6746 displayedcircadian rhythm of potassium uptake only in the dark and notin the light. This rhythm did not persist beyond the secondcycle. (Received June 13, 1978; )     

Energy supply for potassium uptake rhythm in a duckweed, Lemna gibba G3

The energy relationships of the potassium uptake rhythm in aflow-medium culture of a duckweed, Lemna gibba G3, were investigated. Respiratory inhibitors or uncouplers (NaCN, 2,4-dinitrophenoland carbonyl-cyanide m-chlorophenylhydrazon) reduced the mesoror the average rate of potassium uptake, without remarkablydecreasing the amplitude of the rhythm. NaN₃, however, preferablysurpressed the amplitude at a concentration as low as 10^–6M. Both dichloro-phenyldimethylurea and the removal of CO₂ graduallydecreased the average rate of the uptake, although the rhythmicityitself was not eliminated completely in the absence of CO₂.In N₂, the average rate of uptake was reduced to zero, but rhythmwith a small amplitude survived. These observations suggested that respired photosynthates provideenergy for sustaining the average of potassium uptake and thatsome light dependent processes control the amplitude of therhythm. Exogenous sugar could make the potassium uptake rhythmappear for a relatively short time in the dark. ¹This study was carried out in the National Institute for BasicBiology and the Biological Institute, Faculty of Science, NagoyaUniversity (Received October 24, 1979; )     

The structure of pyridinoline,a collagen crosslink

Pyridinoline is an amino acid isolated from collagen and probably serves as a crosslink in collagen fiber. This compound was isolated on a large scale from bovine bone and investigated by ¹H-nmr and ¹³C-nmr spectroscopy, mass spectroscopy and chemical degradation. The structure is proposed on the basis of these data.