Mitochondria in fine afferent nerve fibres of the knee joint in the cat: a quantitative electron-microscopical examination

The distribution of mitochondria, their content and concentration (expressed as the ratio of the mean volume of mitochondria and the surface of the sensory axon) were determined in group-III and-IV nerve fibres innervating the knee joint capsule in the cat. Mitochondria mainly accumulated in axonal swellings (beads) and end bulbs of the terminal branches. Between single nerve fibres, marked differences in the content and the concentration of mitochondria were obtained in proximal portions (inside of the perineurium) and in distal portions (unmyelinated sensory endings). In group-III nerve fibres, the mitochondrial concentration ranged from 0.005 to 0.030 m³/m² (proximal portion) and from 0.016 to 0.080 m³/m² (distal portion). In unmyelinated group-IV nerve fibres, the values also showed a broad variation ranging from 0.001 to 0.011 m³/m² (proximal portion) and from 0.003 to 0.019 m³/m² (distal portion). The wide range of mitochondrial concentrations may reflect different energy consumption during receptive processes: nerve fibres with a low mechanical threshold and a high probability of excitatory events may be rich in mitochondria, whereas fibres with a high mechanical threshold and a low probability of excitatory events may be poor in mitochondria.     

Modelling of sulfur oxidation from elemental sulfur

An elemental S oxidation model has been developed which combines a maximum S release rate with modifiers for temperature and soil moisture conditions. This model has been combined with a pasture growth and CNSP nutrient cycling model to match S oxidation rate to pasture S demand. In two Southern Australian enviroments, 100m elemental S was superior to 200m particles whilst in Northern Australia the 200m particles were superior. These models can be used to match S release to plant demand.     

The effect of monoterpenes on astaxanthin production by a mutant ofPhaffia rhodozyma

Summary The total pigment and astaxanthin content ofPhaffia rhodozyma increased with increasing concentrations -pinene up to 500 l -pinene/l. Above this concentration the total pigment and astaxanthin content as well as the biomass production decreased. The addition of 500 l -pinene/l increased the total pigment content from 1652 g/g to 2201 g/g and the astaxanthin content from 1554 g/g to 1883 g/g. A sharp decrease in maximum specific growth rate occurred above 150 l -pinene/l.     

Induction of apoptosis by gemcitabine in BG-1 human ovarian cancer cells compared with induction by staurosporine, paclitaxel and cisplatin

A variety of chemotherapeutic agents induce cell death via apoptosis. We had shown previously that gemcitabine (2,2-difluorodeoxycytidine) induced an atypical apoptosis in BG-1 human ovarian cancer cells; therefore, further studies were conducted to characterize more precisely gemcitabine-induced apoptosis in BG-1 cells compared to a general inducer of apoptosis, staurosporine. BG-1 cells exposed to 0.5, 1.0 and 10 M gemcitabine for 8 h, or staurosporine (1.0 M) for 6 h, exhibited high molecular weight DNA fragmentation (50 kbp); however, only staurosporine treatment produced internucleosomal DNA fragments (200 bp) in a laddered pattern on the agarose gel. Staurosporine (1.0 M) rapidly induced phosphatidylserine plasma membrane translocation that increased linearly with time as measured by annexin V-FITC binding, and similar kinetics were observed for caspase activation by staurosporine in BG-1 cells. In contrast, 10 M gemcitabine increased phosphatidylserine expression in a small fraction of cells (5–10%) vs. untreated controls over the course of 48 h and significant caspase activity was detected within 12 h of drug exposure. Time-lapse video microscopy of BG-1 cells exposed to 1.0 M staurosporine or 10 M gemcitabine for up to 72 h showed that the morphologic changes and kinetics of cell death induced by these agents differed significantly. We also evaluated the apoptosis induced by paclitaxel (a mitotic poison) and cisplatin (an agent not dependent on cell cycle functions) in BG-1 cells by these methods because these drugs are used clinically to treat ovarian cancer. Our findings demonstrate that the kinetics of apoptotic cell death induced by gemcitabine and other chemotherapeutic agents should be taken into account when designing treatment strategies for ovarian cancer.     

Saccharomyces cerevisiae 2-mum DNA. An analysis of the monomer and its multimers by electron microscopy.

Summary The non-tandem inverted duplication in the 2-m DNA of Saccharomyces cerevisiae has a length of 0.19 m and is located asymmetrically along the molecule. The majority of the dumb-bell structures that are formed upon denaturation and selfannealing of the 2-m monomer consists of the renatured inverted duplication sequences as double stranded stem and two single stranded loops of 0.67 m±0.06 m (S-loop) and 0.86 m±0.05 m (L-loop) length. Two additional size classes which comprised 5–10% of the measured molecules had contour lengths of around 1.7 m and 2.1 m. The smaller dumb-bells contained two S-loops and the larger dumb-bells contained two L-loops as was shown by heteroduplex mapping with an HindIII fragment from the L-loop. Two models which assume illegitimate or site specific recombination, are presented to explain the generation of double S-loop and double L-loop molecules. At least part of the 4-m and 6- circular molecules present in the yeast supercoiled DNA fraction are shown to be dimers and trimers of 2-m monomers, but often with inverted loop segments most probably due to intramolecular recombination between sequences of the inverted duplication.2-m DNA is used to indicate the supercoiled DNA fraction although in our measurements the average monomeric length is 1.9 mPart of this work has been presented at the Conference: The Genetics and Biogenesis of Chloroplasts and Mitochondria, Munich, August, 1976     

In vitro propagation of Rauwolfia micrantha, a rare medicinal plant

Shoot tip and single node explants from young shoots of 1-year old flowering plants of Rauwolfia micrantha Hook. f. were cultured on Murashige & Skoog (MS) medium variously supplemented with 6-benzyladenine (BA) and -naphthaleneacetic acid (NAA). A combination of 13.2 M BA and 2.68 M NAA induced high frequency (77%) formation of up to 3 shoots from each node in 8 weeks. The regeneration of shoot tips from the field-grown plants and in vitro shoots placed horizontally differed. Repeated subculturing of the shoot tips and single nodes at 6-week intervals for over a year in combination of 4.4 M BA and 0.27 M NAA enabled mass multiplication of shoots without any evidence of decline. Rooting of the excised shoots on medium containing 2.6 M NAA was preceded by callus formation. The rooted plants were removed off the callus, hardened off and 80% established in pots. Micropropagated plants displayed uniform morphological, growth, flowering, fruiting and seed germination characteristics.Abbreviations BA 6-benzyladenie - IAA indole-3-acetic acid - IBA indole-3-butyrie acid - 2-ip 2-isopentenyladenine - MS Murashige & Skoog (1962) - NAA -naphthaleneacetic acid     

Fouling of ceramic membranes during microfiltration of model solutions

A model study of the microfiltration of fatty acids (C2 to C8) dissolved in a synthetic ultrafiltrate was performed. Ceramic membranes of 0.1 and 0.2 m were used. Results showed that minerals from the ultrafiltrate were involved in membrane fouling, while fatty acids were poorly rejected.On 0.1 m membranes, modelisation of fouling exhibited two different steps of fouling, a first one due to adsorption of solutes, and a second one involving particles deposit onto the membrane. On 0.2 m membranes, only fouling due to particles deposit was observed in modelisation. Results of fouling and rejection pointed out the great difference between 0.1 and0.2 m membranes.This revised version was published online in October 2005 with corrections to the Cover Date.     

Regulation of antibiotic production by iron and oxygen during defined medium fermentations of Streptomyces clavuligerus

Summary When grown in a chemically defined medium, Streptomyces clavuligerus excreted cephamycin C, in addition to other components, throughout most of the growth phase. Ferrous iron and oxygen are required for the biosynthesis of this antibiotic and the concentration of these cofactors was manipulated to maximize cephamycin C production. The iron content of the chemically defined medium was shown to be sub-optimal for antibiotic production and the addition of 130 g/ml ferrous iron almost doubled the cephamycin C levels to 200 g/ml. When dissolved oxygen was maintained at saturation levels, only 60–80 g/ml cephamycin C was produced, and the intermediate penicillin N accumulated to high levels (50 g/ml). This suggests that the high concentration of dissolved oxygen had a greater effect on the enzymes catalysing the conversion of penicillin N to cephamycin C, than on those involved in the earlier steps of the pathway leading to the formation of penicillin N.     

Intestinal microflora in the deep-sea isopodBathynomus giganteus

Observations with the scanning electron microscope showed that the deep-sea isopodBathynomus giganteus harbors a dense microflora within the digestive tract. The gut microflora is composed of a diversity of microorganisms, including an unusually large bacterial morphotype that predominates almost exclusively in the anterior end of the hindgut. The majority of these large bacteria measured 1.9 m×8.5 m and many reached a size of 2.0 m×10.0 m.     

Fine structure of early previtellogenic oocytes in Mugil (Liza) auratus Risso, 1810 (Teleostei,Mugilidae)

Summary Sequential cytological events at the onset of previtellogenesis were studied in oocytes from 12 m to 70 m in diameter of golden grey mullet. The main cytological changes observed (increase in size of cell, nucleus, nucleolus and increase in number of nucleoli, RNP particles, nuage and mitochondria) provide evidence for important synthetic processes in an early preparatory phase of oocyte development.Somatic cells (pre-follicle, follicle and thecal) are also described.     

Effect of thidiazuron on vegetative tissue-derived somatic embryogenesis and flowering of bamboo Bambusa edulis

Current research on somatic embryogenesis of bamboo uses reproductive tissue as explants. However, it was hard to obtain the explant. Shoots of a local accession (3–4 m high) were used for multiple shoot production. In order to obtain embryogenic callus, nodal and internodal tissues from in vitro plantlets were placed on Murashige and Skoog (MS) medium supplemented with 9.2 M kinetin (KN), 13.6 M 2,4-dichlorophenoxyacetic acid (2,4-D), 0.1% (v/v) coconut milk, and 6% (w/v) sucrose. We studied the effects of sucrose and thidiazuron (TDZ) on callus proliferation. Optimal additives to the MS medium for embryogenic callus proliferation were 0.046 M TDZ, 13.6 M 2,4-D and 3% (w/v) sucrose. TDZ also promoted the germination of bamboo somatic embryos. The germination rate of the somatic embryos exceeded 80% on MS-based medium supplemented with 0.455M TDZ. Naphthaleneacetic acid (NAA) reduced germination. Well-developed plantlets were successfully transferred to soil. There was no albino mutant in subsequent culture. In vitro regenerants and potted plants flowered, but no seeds were produced.     

Changes with age in the absorption spectrum of chlorophyll α in a diatom

Summary Absorption spectra of a young and an old culture of the diatom Pheodactylum tricornutum were measured in thin layers between two opal glass sheets. The spectra at 24° and at -196°C were replotted to give equal areas from 730–625 m to allow direct comparison. At 24°C the spectrum for the difference between the two cultures had a negative component of 18 m half width centered at 675 m and a positive region of W_0.5=26 m near 700 m.The spectra at -196°C may be somewhat distorted by clumping of the cells during freezing but nevertheless the 16 day culture clearly showed a smaller proportion of Ca 670 to Ca 680. This older culture has a shoulder due to a 707 m component. The difference curve at -196°C shows the decrease of an unsymmetrical band peaking at 669 m and an increase at 695 m in addition to the 707 m component. Due to the possibility of distortion, the presence of an actual component at 695 is doubtful in these particular cultures.The room temperature spectrum in the chloropyhll a region for the 5 day culture can be closely fitted by a single probability curve at 675 m having a half-width of 31 m. The sum of two components, with widths more reasonable for chlorophylls, also matched the data well enough. These two probability curves, of 22 m half width, centered on 669 and 683.2 m and had a height ratio, h₆₆₉/h₆₈₃ of 1.18. In the 16 day culture the ratio for these bands changed to 1.11 and there was extra absorption around 700 m.Dedicated to Professor C. B. van Niel on the occasion of his 70th birthday     

In vitro culture of Aloe Barbadensis Mill.: Micropropagation from vegetative meristems

A method for rapid and highly effective plant micropropagation from vegetative meristems was established for Aloe barbadensis Mill. Plant micropropagation was achieved culturing apices on medium containing 1.1 M 2,4-dichlorophenoxyacetic acid and 2.3 M kinetin for 15–30 days. High morphogenetic ability was maintained by transferring explants (after 60 days) on media containing 0.11 M 2,4-dichlorophenoxyacetic acid and 2.2 M 6-benzylaminopurine.     

Image processing technique for measuring specific growth rates of Gibberella fujikuroi

Summary Two methods were compared for estimating of Gibberella fujikuroi grown with different proportions of glucose and starch. They were, =Ln2 (V_r/Le) on Petri dish (V_r= rate of tip extension and L_e= mean hyphal length) and, ₂=d (LnX)/dt in stirred fermenter. Values of ₁ and ₂ were in close agreement with each other.     

Guanylyl Cyclase Participates in the Mechanism of Glutamatergic Modulation of Acetylcholine Non-Quantum Release in the Rat Neuromuscular Junction

It was shown that glutamate (10 M to 1 M) suppresses in a dose-dependent manner the non-quantum release of acetylcholine from rat motor nerve endings; the release intensity was estimated by the H effect. The action of glutamate was completely eliminated by the blockade of guanylyl cyclase by 1 M ODQ. An increase in the intracellular cGMP concentration by 1 M dibutyryl-cGMP reduced the H effect in a similar manner as glutamate did.     

The quantitative analysis of chromosome pairing and chiasma formation based on the relative frequencies of M I configurations

Whilst reliable estimates of chiasma frequencies can usually not be obtained, the probability (b) of a chromosome arm to be bound by at least one chiasma can often be determined. In the absence of interference this probability equals (1–e ^–2), where 2 is the average chiasma frequency of the chromosome arm and the average crossover frequency or map length. In the presence of interference is shown to retain its genetic meaning as an additive metric that may describe the chromosome arm or other distinctive chromosome segment in terms of genetic recombination. It is a form of potential map length, comparable to, but numerically different from the regular map length. It is termed provisionally crossing-over potential.A chromosome with armsm andn with crossing-over potentials and will form ring bivalents with a frequency (1–e ^–2).(1–e ^–2); open bivalents with a frequency (1–e ^–2).e ^–2+(1–e ^–2).e ^–2; univalent pairs with a frequencye ^–2.e ^–2. Estimates of these frequencies yield equations from which and may be solved. In rye (Secale cereale) their ratio (q) is approximately two and differs from the mitotic arm length ratio of 1.4, indicating localization of chiasmata in the long arms.Graphs are given to show how, with constantq, the relation between the probabilitiesb _m andb _n of the two arms being bound changes with changing averageb.Data are presented on chiasma frequencies in M I, and compared with the frequencies expected in the absence of interference to give an impression of the degree of interference. Apparent fusion of chiasmata simulates interference.     

The effects of triethyl lead on the development of hippocampal neurons in culture

Triethyl lead is the major metabolite of tetraethyl lead, which is used in industrial processes and as an antiknock additive to gasoline. We tested the hypothesis that low levels of triethyl lead (0.1 nmol/L to 5mol/L) interfere with the normal development of cultured E18 rat hippocampal neurons, possibly through increases in intracellular free calcium ion concentration, [Ca²⁺]_in. The study assessed survival and differentiation using morphometric analysis of individual neurons. We also looked at short-term (up to 3.75-h) changes in intracellular calcium using the calcium-sensitive dye fura-2. Survival of neurons was significantly reduced at 5 mol/L, and overall production of neurites was reduced at 2 mol/L. The length of axons and the number of axons and dendrites were reduced at 1 mol/L. Neurite branching was inhibited at 10 nmol/L for dendrites and 100 nmol/L for axons. Increases in intracellular calcium were observed during a 3.75-h exposure of newly plated neurons to 5 mol/L triethyl lead. These increases were prevented by BAPTA-AM; which clamps [Ca²⁺]_in at about 100 nmol/L. Culturing neurons with BAPTA-AM and 5 mol/L triethyl lead did not reverse the effects of triethyl lead, suggesting that elevation of [Ca²⁺]_in is not responsible for decreases in survival and neurite production. Triethyl lead has been shown to disrupt cytoskeletal elements, particularly neurofilaments, at very low levels, suggesting a possible mechanism for its inhibition of neurite branching at nanomolar concentrations.Abbreviations BAPTA-AM 1,2-bis(2-aminophenoxy)ethane-N,N,N,N-tetraacetic acid acetoxymethyl ester - [Ca²⁺]_in intracellular free calcium ion concentration - DMSO dimethyl sulfoxide - E18 embryonic day 18 - FBS fetal bovine serum - fura-2AM fura-2 acetoxymethyl ester - HBSS Hanks' Balanced Salt Solution - MEM Eagle's Minimum Essential Medium     

Callus induction and plant regeneration in Vetiveria zizanioides

Callus induction was obtained from basal parts of Vetiveria zizanioides Stapf. leaves cultured on Murashige and Skoog (MS) medium supplemented with 9.0 M 2,4-dichlorophenoxyacetic acid (2,4-d), 5.7 M indoleacetic acid (IAA) and 4.6 M kinetin. Calli were maintained on MS medium with the addition of 0.9 M 2,4-d and 2.3 M kinetin. Shoot formation was obtained from fast growing 14-day-old callus on the same basal medium supplemented with 0.9 M 2,4-d and 9.3 M kinetin. Embryo-like structures were observed. When transferred to basal medium, shoots readily developed roots. Fully developed regenerated plants were then successfully established in soil.     

Micropropagation and ecorestoration of Vanda spathulata,an exquisite orchid

Node explants collected from flowering plants of Vanda spathulata, an endemic and exquisite orchid of Peninsular India and Sri Lanka, were cultured in Mitra medium with combinations of 4.4–88.8 m 6-benzyl adenine (BA) and 0.0–114.2 m indole-3-acetic acid (IAA). Combinations of 44.4 m BA with 17.1 or 28.5 m IAA and 66.6 mM BA with 28.5 or 40.0 m IAA induced maximum formation of 12.6 and 12.1 shoots / node, respectively, in a 6-month period. Subcultured nodal explants produced maximum of 6.1 shoots at combinations of 22.2–44.4 m 21 BA and 5.7–28.5 m IAA. Rooting of shoots occurred in medium containing 75 g l^–1 banana pulp and 5.7 m IAA within 3–9 weeks. Plantlets of 2–5 cm length possessing two to five roots established easily in community pots at 80–90% rates without hardening. Community potted plants introduced into forest segments at Ponmudi and Palode in Southern Western Ghats of India established at a rate of 50–70%.     

The spermatozoon of Oikopleura dioica Fol (Larvacea,Tunicata)

Summary The spermatozoon of Oikopleura dioica is about 30 m long, with a spherical head, about 1 m wide, a 3 m long and 1 m wide midpiece, and a 25 m long tail with a tapered end piece. The head contains a nucleus with the chromatin volume limited to about 0.1 m³. A small acrosome is found in an anterior inpocketing, and a flagellar basal body in a posterior inpocketing of the nucleus. The midpiece contains a single mitochondrion with the flagellar axoneme embedded in a groove along its medial surface. The flagellar axoneme has the typical 9 + 2 substructure, and the basal body the typical 9+0 substructure. A second centriole and special anchoring fibres are absent.