Relationship between calcium and agar on vitrification and shoot-tip necrosis of quince (Cydonia oblonga Mill.) shoots in vitro

Shoot-tip cultures of Quince C (Cydonia oblonga Mill.) initiated on Murashige & Skoog (MS) medium containing 5 M BA and 0.6% Phytagar showed both shoot-tip necrosis and severe vitrification. Culturing explants on medium containing 1.2% Phytagar and Ca levels of 3 mM (MS medium), 18 mM and 30 mM showed a decrease in growth with increasing medium Ca levels, being especially severe at 30 mM. The Ca content of the explants increased linearly with increasing medium Ca. Culturing explants on medium containing 3 mM, 9 mM, and 18 mM Ca at 0.6, 0.9, and 1.2% agar resulted in reduction in growth, shoot-tip necrosis, and vitrification when either factor was increased. The reduction in shoot-tip necrosis could be accounted for primarily by an increase in medium Ca levels but may also be affected by a change in explant growth. Increasing Ca concentration in the medium resulted in a linear increase in explant K, Ca, Mg, and B levels and a decrease in Mn and Na. Although increasing medium Ca or agar levels reduced vitrification, it is unclear whether they were the direct cause of the reduction in vitrification or whether this response was an effect of the reduction in culture fresh weight.Approved by publication by the Director, West Virginia Agriculture anf Forestry Experimental Station as Scientific Article No. 2199     

噬菌蛭弧菌简易保存方法的研究

本文报道了噬菌蛭弧菌在自来水宿主软琼脂中,于4℃环境(冰箱)存活的时间.发现噬菌蛭弧菌在自来水宿主软琼脂中,于4℃冰箱中保存,至少可以存活3个月以上,一般为5～8个月左右,最长时间可达18个月。但在自来水宿主双层琼脂平板上形成的噬斑数目,随着保存时间的延长,则有不同程度的减少。     

Agar yield and quality of Gracilaria chilensis (Gigartinales,Rhodophyta) in tank culture using fish effluents

Tank cultivation of Gracilaria using fish effluents has permitted a production of 48 kg m^–2 yr^–1 and can reduce the dissolved nitrogen loads in the seawater. We report the yield, gel strength, gelling and melting point of agar from Gracilaria cultivated in tanks with seawater previously utilized in intensive, land-based salmon cultures and compared to a control using directly pumped seawater, over a study period of 22 months. The results show that the highest agar yield (20 to 22%) was obtained when Gracilaria was cultivated with pure seawater as compared to the fish effluents. The gel strength, gelling and melting point were higher in the agar obtained from algae cultured with fish effluents. During the spring, the gel strength, gelling and melting point increased in tanks with fish effluents and decreased in tanks with a supply of pure seawater.     

A new chemical tool for characterization and partial depolymerization of red algal galactans

Complete acid hydrolysis of red algal galactans in the presence of borane - 4-methylmorpholine complex has been shown to prevent the acid degradation of 3,6-anhydrogalactose derivatives by their reduction to the corresponding 3,6-anhydro-galactitols, whereas all the other monosaccharides are liberated essentially in the non-reduced form; the reductive hydrolysis products may be determined quantitatively using gas-liquid chromatography (GLC). The method is recommended for preliminary characterization of the polysaccharide composition of red algal biomass. Partial acid hydrolysis of galactans in the presence of the same reducing agent gives rise to reduced oligosaccharides having terminal 3,6-anhydrogalactitol residues. Based on this reaction, the attribution of unknown galactans to the agar or carrageenan groups is possible by partial reductive hydrolysis of small samples of algal biomass with subsequent identification of agarobiitol or carrabiitol acetates by GLC. Sulfate groups are substantially retained under partial reductive hydrolysis conditions; the isolation by liquid chromatography and elucidation of structures of reduced sulfated oligosaccharides may be of great value for the structural analysis of complex red algal galactans.     

Seasonal variation in the physical properties of agar and biomass of Gracilaria sp. (chorda type) from Tosa Bay,southern Japan

Plants of Gracilaria sp.(chorda type), which grow along the coast of Uranouchi Inlet in Tosa Bay, southern Japan, showed the highest biomass in the summer (26 °C to 31 °C) and spring season (15.1 °C to 24.9 °C). Maximum biomass was 6952 g m^–2 in July, but gradually decreased in the autumn (30.5 °C in September to 20 °C in November) and winter (19.5 °C in December to 14.9 °C in February). Variation in yields and gel strength of the agars, were shown to depend on the time in the season. After alkali treatment (5% NaOH, 2 h) at three different temperatures (70, 80, and 90 °C), the agars showed gel strengths essentially that of commercial grade agars, with the best gel obtained at 80 °C. Maximum gel strength (1455 g cm^–2 of 1.5% agar gel) occurred in winter when the biomass and agar yield were low. Minimum gel strength was in spring. Gel strength was inversely correlated with agar yield, but was positively correlated with apparent viscosity. Maximum viscosity was 40 cP. in December. Gelling temperatures, pH of 1.5% agar gel, and moisture content in agars showed little variation.     

Annual variations of the biochemical composition of Gelidium latifolium (Greville) Thuret et Bornet

Agar, floridean starch, protein, ash and water content in Gelidium latifolium from nature were followed monthly over one year. Comparison of variations in these contents, algal growth and cytological observations enable us to establish a cycle for agar synthesis. In autumn, after reproduction of alga, there is an active algal growth period with agar synthesis and utilization of floridean starch. In winter, synthesis is shifted toward protein accumulation while there is a partial agar hydrolysis. In spring another active growth period of the alga occurs with accumulation of floridean starch and synthesis of agar. In summer and during reproduction, there is a depletion of thalli nitrogen content while the agar synthesis pauses.     

Embedding of Neural Tissue in Agarose or Glyoxyl Agarose for Vibratome Sectioning

Agarose was used to embed the brain or spinal cord of lampreys or rats before cutting vibratome sections. Agarose embedding was compatible with immunocytochemistry or the use of horseradish peroxidase as a neuroanatomical tracer. Concentrated agarose with high intrinsic gel strength was optimal for embedding glutaraldehyde fixed neural tissue. A quick procedure was to blot tissue and embed in 5% (w/v] Sigma type I-A or Litex type LSL agarose at 45-55 C dissolved in 50 mM neutral-pH TFUS buffer before cutting 50-100 μm vibratome sections. An alternative procedure that improved retention of tissue sections in the agarose was to rinse the tissue in H₂0, blot and embed in 5% (w/v] Sigma type I-A or Litex type LSL agarose at 45-55 C dissolved in H₂0, then equilibrate the block overnight in buffer. Phosphate buffer prevented complete dissolving of agarose. Tissue could be covalently linked to the embedding matrix using a novel aldehyde-derived agarose (NuFix® FMC BioProducts). Slices of spinal cord from neonatal rats could be cut after embedding in 5% FMC Seaprep® agarose in rat Ringer's at 23-26 C.     

FORMATION OF NUCLEOSIDE DIPHOSPHATE MONOSACCHARIDES (NDP-SUGARS) BY THE AGAROPHYTE PTEROCLADIA CAPILLACEA (RHODOPHYCEAE)1

The following nucleoside diphosphate monosaccharides (sugar nucleotides) were identified by HPLC from Pterocladia capillacea Born and Thur.: ADP-glucose, UDP-glucose, UDP-d -galactose, and GDP-glucose + mannose. GDP-l -galactose was not identified due to the lack of a standard. Several extraction methods were evaluated for their efficacy. A freeze/ thaw (liquid N₂) step fallowed by formic acid (1 M) extraction, reduced pressure evaporation, and solubilization in water was the preferred method. Differences in media nitrate that resulted in different tissue-N levels (1.8, 2.3, and 3.5% dry wt) and agar yields (34, 31, and 28% dry wt, respectively) also resulted in a marked difference in UDP-d -galactose and ADP-glucose tissue levels (decrease with increasing tissue-N) while the levels of the other sugar nucleotide agar precursors remained unchanged. Activities of UDP-glucose, GDP-glucose, and GDP-mannose pyrophosphorylases, and UDP-D-glucose-4-epimerase were detected in cell-free extracts using unlabeled and ¹⁴C-labeled substrates. This study-strongly supports the proposition that the d -galactose component of agar is synthesized via G-1-P → UDP-glucose→ UDP-d -galactose and that, the l -galactoae component is produced via mannose-1-P → GDP-mannose → GDP-l -galactose.     

Dictyocaulus viviparus: Migration in agar of larvae subjected to a variety of physicochemical exposures

Dictyocaulus viviparus larvae were exposed to ox bile and CO₂ at intervals during their cultivation to the infective stage. Preinfective and young infective larvae were stimulated by CO₂. Bile slightly inhibited preinfective larvae, but stimulated the infective stage. Old coiled, resting infective larvae were stimulated by bile down to a concentration of 10 ppm of bile dry matter, by vertebrate biles of pig, sheep, newborn calf, cow, guinea pig, dog, and chicken, as well as by defatted bile dry matter and by glyco-, tauro-, glycodeoxy-, and taurodeoxycholates. Continuous bile exposure appeared necessary to maintain high larval activity. A high pCO₂ as well as a low redox potential potentiated the effect of bile, but had no effect alone. Exposure to pepsin-HCl and to trypsin had only a minor stimulatory effect.     

The use of a partition locus to increase stability of tryptophan-operon-bearing plasmids in Escherichia coli

The stability of different derivatives of plasmid vectors pBR322 and pACYC184 carrying the tryptophan operon of Escherichia coli was monitored in various media. It was found that in the absence of any special selective pressure, all plasmids were lost from the culture. The stability varied depending both on the orientation of the inserted tryptophan fragment and the growth media used. The pBR322::trp+ plasmids were lost at an average frequency of 0.3 to 0.8% per cell generation, while the pACYC184::trp+ plasmid was lost at a rate higher than 5%. In all cases the whole plasmid was lost at a rate higher than 5%. In all cases the whole plasmid was lost, indicating a high stability of the plasmid::cloned DNA as such. To increase the stability of the cloning vectors, the partition locus of plasmid pSC101 was added to both the pBR322::trp+ and pACYC184::trp+ plasmids. The addition of this gene increased the replicon stability at least 3- to 10-fold, with the pBR322::trp+-par+ plasmids being the most stable. Also in this case, the stability was dependent on the plasmid type and on the growth medium. In no case was there a discoordinate loss of the antibiotic-resistance and tryptophan genes from the vectors.