Epoxy derivatives of aromatic polycyclic hydrocarbons. The preparation and metabolism of epoxides related to benzo[a]pyrene and to 7,8- and 9,10-dihydrobenzo[a]pyrene

Products that appeared to be mainly benzo[a]pyrene 7,8-oxide and benzo[a]pyrene 9,10-oxide were synthesized and their chemical and biochemical properties were investigated. The oxides were unstable and readily rearranged to phenols. They were converted by rat liver homogenates and microsomal preparations into phenols and dihydrodiols, but glutathione conjugates were not formed in appreciable amounts. The dihydrodiols formed from benzo[a]pyrene 7,8- and 9,10-oxide by rat liver microsomal preparations were identical in their chromatographic and spectrographic properties with dihydrodiols formed when benzo[a]pyrene was metabolized by rat liver homogenates. 9,10-Dihydrobenzo[a]pyrene 7,8-oxide and 7,8-dihydrobenzo[a]pyrene 9,10-oxide were also synthesized. They were converted by rat liver homogenates and microsomal preparations into the related cis- and trans-dihydroxy compounds. Glutathione conjugates were formed from the oxides by rat liver homogenates. Both 7,8- and 9,10-dihydrobenzo[a]pyrene were metabolized by rat liver homogenates to mainly the trans-isomers of the related dihydroxy compounds. In experiments with boiled homogenates, the benzo[a]pyrene oxides were converted into phenols, whereas the dihydrobenzo[a]pyrene oxides yielded small amounts of the related dihydroxy compounds.     

Stability of the biocatalysts of L-aspartic acid synthesis based on immobilized Escherichia coli cells

Experiments were carried out to investigate the process of a continuous enzymatic synthesis of L-aspartic acid from ammonium fumarate in uniform filling flow reactors. Escherichia coli (Soviet strain 85) cells immobilized in polyacrylamide gel granules reinforced by a solid carrier were used as biocatalysts. The conditions, under which a high aspartase activity of the biocatalyst and a stable hydrodynamic performance of the reactor were maintained, were determined. The main kinetic characteristics of a continuous performance of the reactor for 150 days were obtained.     

Establishment of a SPF colony of human apo(a) transgenic rabbits by frozen-thawed embryo transfer.

In the present study, embryo transfer was performed using frozen-thawed embryos to establish a SPF colony of human apolipoprotein (a) (apo(a)) transgenic rabbits. Apo(a) transgenic rabbits were kept under conventional condition and were infected with Bordetella bronchiseptica. Embryos at the morula stage were collected and stored in liquid nitrogen. After thawing, the in vitro survival rate was 84.6%, and 125 morphologically normal embryos were transferred to 6 SPF recipient rabbits. Four rabbits became pregnant and 23 live pups were born. PCR and Western blot analyses revealed that 9 of 23 pups were transgenic and expressed apo(a) protein. Microbiological tests showed all rabbits were free from infections. We succeeded in establishing a SPF colony of apo(a) transgenic rabbits. These rabbits are now maintained under a barrier system and are available for medical research.     

Haemangioblastoma: histological and immunohistological study of an enigmatic cerebellar tumour

Paraffin-embedded blocks of 36 cerebellar haemangioblastomas were reacted with a panel of antibodies including glial fibrillary acidic protein, vimentin, epithelial membrane antigen, cytokeratin, Factor VIII, a neuroendocrine marker and with Ulex europaeus. agglutinin The main histological features, apart from the characteristic large abnormal vessels, were a prominent reticulin network, a cystic architecture and cellular and nuclear polymorphism. Two cell types were identified: endothelial and stromal. Twenty tumours were positive for glial fibrillary acidic protein because of included or reactive astrocytes as well as positive stromal cells. Vimentin was positive in all tumours with a diffuse distribution and a somatic pattern; blood vessels, stromal cells and reactive astrocytes were strongly positive. Factor VIII and Ulex europaeus agglutinin reactivity were present in a similar pattern of staining in endothelium and in five cases there were stromal cells that were positive with the latter. We were not able to ascertain the histogenesis of the stromal cell, which remains enigmatic.     

The effect of genotype on response thresholds to sucrose and foraging behavior of honey bees (Apis mellifera L.)

Honey bee foragers were tested for their proboscis extension response (PER) to water and varying solutions of sucrose. Returning pollen and nectar foragers were collected at the entrance of a colony and were assayed in the laboratory. Pollen foragers had a significantly higher probability of responding to water and to lower concentrations of sucrose. Bees derived from artificially selected high- and low-pollen-hoarding strains were also tested using the proboscis extension assay. Returning foragers were captured and tested for PERs to 30% sucrose. Results demonstrated a genotypic effect on PERs of returning foragers. The PERs of departing high- and low-strain foragers were consistent with those of returning foragers. The PERs were related to nectar and water reward perception of foragers. High strain bees were more likely to return with loads of water and lower concentrations of sucrose than foragers from the low pollen strain. Low-strain bees were more likely to return empty. We identified a previously mapped genomic region that contains a variable quantitative trait locus that appears to influence sucrose response thresholds. These studies demonstrate a gene-brain-behavior pathway that can be altered as a consequence of colony-level selection for quantities of stored food. Accepted: 3 September 1997     

A survey of angiosperm species to detect hypodermal Gasparian bands. II. Roots with a multiseriate hypodermis or epidermis

PETERSON, C. A. & PERUMALLA, C. J., 1990. A survey of angiosperm species to detect hypodermal Casparian bands. II. Roots with a multiseriate hypodermis or epidermis.
Roots of 25 species which had either a multiseriate hypodermis or a multiseriate epidermis were tested for the presence of a hypodermal Casparian band. All species save one were in the Liliopsida and six were orchids with both soil and aerial roots. Lignosuberized hypodermal Casparian bands were present in all species tested; those with a biseriate hypodermis had bands in both layers and of those with a multiseriate hypodermis, the three species which were tested had bands in every layer. Although Casparian bands can often be recognized by the presence of sinuous walls in longitudinal views of uniseriate hypodermal layers, these sinuosities were not evident in multiseriate hypodermal layers containing Casparian bands. The lack of air spaces, once thought to be a characteristic feature of the hypodermis, did not hold true for some members of the Liliopsida. All walls of the hypodermis were suberized, indicating that suberin lamellae were probably present in addition to Casparian bands. We recommend using the term 'exodermis' to refer to a hypodermis which has a Casparian band. Epidermal walls of non-orchid roots were suberized whereas those of orchids were lignified. Regardless of their type of modification, all epidermal walls were permeable to the apoplastic dye, Cellufluor.     

基于线粒体COⅠ和Cytb基因序列研究粉蝶科七属间的系统发生关系

【目的】为了探讨粉蝶科Pieridae 7属的系统进化关系。【方法】基于线粒体COⅠ(609 bp)和Cytb(393 bp)基因部分序列,以眼蝶科的2个物种为外类群,运用UPGMA和ME法重建分子系统树。【结果】联合基因构建的分子系统树显示:外群牧女珍眼蝶Coenonympha amaryllis(Cramer)和阿芬眼蝶Aphantopus hyperantu(Linnaeus)构成一独立支系,可以作为外群;云粉蝶属和粉蝶属姊妹关系构成一分支,亲缘关系较近;襟粉蝶属与钩粉蝶属形成姐妹关系,亲缘关系较近。【结论】成功重建了粉蝶科7属的系统进化关系。     

The use of PIT telemetry to study movements of ammocoetes and metamorphosing sea lampreys in river beds

Passive integrated transponder (PIT) tags were surgically implanted in 118 sea lamprey Petromyzon marinus ammocoetes which were left to recover in the laboratory for 2 months. During this period 55 individuals started to metamorphose. In the late summer of 2002 the tagged animals were released in a small tributary of the River Mondego, Portugal, and were regularly monitored for a period of 2 months using a portable PIT tag reader. The distribution of the released animals changed from an initial uniform pattern to a random distribution, and then to an aggregated pattern. At the end of the first week 60% of the tagged sea lampreys had already left the study area, indicating their dynamic behaviour. Ammocoetes were more active than metamorphosing sea lampreys, and downstream movements were more frequent when compared to the upstream ones, which were usually a short distance. In order to determine the influence of the dark‐light cycle in the diel activity rhythms, 10 tagged sea lamprey ammocoetes were released in a tank (2000 l capacity) and their position monitored twice a day, for a period of 1 month. Ammocoetes locomotor activity appeared to be conditioned by circadian rhythms, and they were particularly active during darkness.     

The interaction of the causative agent of melioidosis with the host's alveolar macrophages]

Studies were carried out on guinea pigs and albino rats, intranasally infected with P. pseudomallei C-141. The cells of bronchovesicular exudate were obtained from animals 1, 4 and 24 hours after infection. Electron microscopy was applied to study the process of interaction of the agent and alveolar macrophages. Bacteria were shown to form a capsule which permitted avoiding phagocytosis, when entering the host respiratory system. Microbes that failed to form a capsule were absorbed by macrophages and enclosed in a phagosome. Then some bacteria were destroyed by the lysosomal enzymes, the other synthesized a capsule, which protected them against the effect of phagolysosome content. There were also such microbes which escaped from a phagosome prior to fusion with lysosomes and parasitized in phagocytic cytoplasma forming a capsule there. By the end of the first 24 hours of observation the intact encapsulated microbe species were found to prevail in the host cells.     

Behavioral contrast of a complex operant

Two experiments were conducted in which pigeons were trained to perform a complex operant consisting of a peck to one key followed by a peck to another key. In the first experment this performance was reinforced on a variable-interval schedule and the birds were then subjected to a multiple schedule in which the variable-interval was alternated with extinction. The first two pigeons trained showed some deterioration of the cohesiveness of the response sequence. After measures were taken to correct this the pigeon gave evidence of behavioral contrast in a condition where sessions with discrimination were alternated rapidly with sessions with no discrimination (variable-interval only). Another two birds were trained on variable-interval followed by discrimination. One of these birds showed evidence of contrast but the results of the other were not clear.Experiment II was a three phase experiment in which animals were first trained to make the complex response. In the second phase they were extinguished by providing noncontingent reinforcement in each of two components. In the third phase reinforcement was removed from one component, providing for a stimulus-reinforcer contingency. In the third phase the complex response reappeared temporarily.The results of these two studies indicate that a complex response may show behavioral contrast and that it may be enhanced by stimulus-reinforcer contingencies if it has already been trained.     

Purification of two muscle enzymes by chromatography on immobilized ferric ions

Two enzymes, glycogen phosphorylase and lactate dehydrogenase, were purified simultaneously in a single step. Ferric ions immobilized on a chelating gel were used as the adsorbent. Adsorption and desorption steps were accomplished by changes in buffer composition. The recoveries were better than 80% and the capacities were about 5 mg of protein per milliliter of adsorbent. The procedure worked well both on a small and on a preparative scale. The homogeneity of the purified enzymes was checked by FPLC.     

Reduced birth intervals following the birth of children with long-term illness: evidence supporting a conditional evolved response

Human birth interval length is indicative of the level of parental investment that a child will receive: a short interval following birth means that parental resources must be split with a younger sibling during a period when the older sibling remains highly dependent on their parents. From a life-history theoretical perspective, it is likely that there are evolved mechanisms that serve to maximize fitness depending on context. One context that would be expected to result in short birth intervals, and lowered parental investment, is after a child with low expected fitness is born. Here, data drawn from a longitudinal British birth cohort study were used to test whether birth intervals were shorter following the birth of a child with a long-term health problem. Data on the timing of 4543 births were analysed using discrete-time event history analysis. The results were consistent with the hypothesis: birth intervals were shorter following the birth of a child diagnosed by a medical professional with a severe but non-fatal medical condition. Covariates in the analysis were also significantly associated with birth interval length: births of twins or multiple births, and relationship break-up were associated with significantly longer birth intervals.     

Eimeria apsheronica in the goat: endogenous development and host cellular response

Most first generation schizonts of Eimeria apsheronica developed in the jejunum; others were distributed throughout the small intestine and occasionally in the caecum. Some were also found in the mesenteric lymph nodes, which were oedematous and haemorrhagic. In the intestine, haemorrhage and congestion were seen before parasites were detected, and continued throughout all later stages. Schizonts occurred in the lamina propria and occasionally in the submucosa, where they sometimes caused a cellular inflammatory response. Schizonts were first seen at 8 days post-infection (DPI); they had poorly defined nuclei and were enclosed in a capsule-like wall. At 16 DPI, many had matured, had a mean size of 125 x 82 microns, and were filled with numerous spindle-shaped merozoites, which were in ranks and loops. At 18 and 20 DPI, when small white lesions (1-3 mm in diameter) were observed in the jejunum and elsewhere in the small intestine, a second generation of schizonts, macrogametes, microgametocytes and maturing oocysts were seen, in the epithelial cells of the small intestine and caecum. Their mean sizes, respectively, were: 26.2 x 18.9, 24.7 x 18.5, 30.2 x 21.7 and 26.6 x 19.3 microns. Macrogametes contained basophilic central and eosinophilic peripheral granules. The sexual stages were associated with a generalized cellular inflammatory response.     

Changes in the jugular haematocrit of sheep during feeding.

Intact and splenectomized sheep with and without a rumen fistula were used to investigate changes in the jugular blood haematocrit and plasma osmolality during hourly and once-daily feeding regimes. Osmolality was also estimated in the ruminal fluid of fistulated sheep with spleens. Haematocrit decreased in sheep with spleens before they were given a once-daily feed; it increased when these sheep started to feed, reaching a maximum increase of 13% after 30 min of feeding; it decreased during the remaining 45 min of feeding time and usually continued to decrease after feeding stopped. These changes were not due to diurnal influences. Splenectomized sheep fed once daily showed only small decreases in haematocrit before they were fed. Increases occurred with the onset of eating but they were smaller (7%) than in intact sheep and were of shorter duration. In hourly fed sheep with spleens, haematocrit decreased in the early stages of sampling in a manner similar to that for sheep fed once daily. The changes in haematocrit that did occur were not related in any obvious manner to the feeding regime. The haematocrit in splenectomized sheep fed hourly was stable throughout feeding. Variations in the haematocrit in splenectomized sheep, equivalent to a range of 13% in one of them, were observed in a series of blood samples obtained during a 5-h period remote from the feeding time. Large increases occurred in osmolality of ruminal fluid when sheep were fed daily and this was abolished by hourly feeding. Plasma osmolality in sheep fed once daily increased slowly. Maxima occurred after 100 min from the start of eating and were 7% greater than prefeeding values. Only minor changes were observed when these sheep were fed hourly.     

Fine needle aspirates of follicular lesions of the thyroid gland. The intermediate-type smear

In order to evaluate fine needle aspirates of thyroid lesions with features intermediate between those of follicular neoplasms and colloid nodules, 38 aspirates in which a definitive diagnosis had not been made were reviewed. On review, ten aspirates were excluded from the "intermediate" category; seven were reclassified as unsatisfactory and one as a cellular colloid nodule. Two papillary carcinomas showed a complex pattern not identified in smears from other lesions; these aspirates were also classified separately for independent evaluation. The remaining 28 aspirates were characterized by syncytial-type tissue fragments with mild nuclear atypia. The association of syncytial-type tissue fragments and orderly sheets and fragments forming a honeycomb pattern in the same aspirate indicated a colloid nodule, though a two-disease process could not be excluded. Of the aspirates containing only syncytial-type tissue fragments, 50% were from adenomas, 25% were from carcinomas, and 25% were from colloid nodules. Criteria to distinguish between the various follicular lesions were not identified in these smears.     

The isolation of evolutionarily conserved Eag I end-clones from mouse chromosome 17 using cloned DNA.

To isolate DNA markers from mouse chromosome 17, a genomic phage library was constructed from the mouse-hamster CMGT cell hybrid RcE-B52. This hybrid contains a chromosomal fragment from the distal end/flanking region of the t complex on mouse chromosome 17. Recombinants of mouse origin were identified by using a panel of mouse-specific repetitive sequences as a probe. A total of 1,500 mouse phage recombinants were isolated. These were found to represent 250-300 individual recombinants, comprising about 4 Mbp of cloned mouse DNA. The pooled mouse recombinant phages were used to construct an Eag I end-library. This was achieved by the specific insertion of a marker plasmid in Eag I recognition sites when present in the mouse inserts of the recombinant phages. The Eag I end-fragments were subsequently subcloned using a simple procedure taking advantage of the inserted plasmid. A total of 56 individual Eag I end-fragments were identified. These were found to contain recognition sites for rare cutting enzymes at high frequency. A large proportion (73%) were found to be evolutionarily conserved in human DNA. Furthermore, a significant fraction of these fragments, two of six tested, appears to detect specific cDNAs in a 8.5-day mouse embryo cDNA library.     

Open-Face, Epoxy Embedding of Single Cells for Ultrathin Sections

Intact stamens of Tradescantia were fixed, dehydrated, and infiltrated with an epoxy resin. Each stamen was then put into a drop of resin on a microscope slide, which was transferred to the stage of a dissecting microscope so that individual hairs could be detached from the filament with fine tungsten needles. The detached hairs were transferred to drops of resin ca. 2 mm in diameter (6 or 7 in each of two rows) lying on a slide heavily coated with evaporated carbon. Polymerization was carried out in an oven until the resin attained a degree of viscosity that permitted orientation of the isolated hairs (by using a compound microscope) without their subsequent dislocation. When the small drops of resin had hardened after further polymerization, the positions of the hairs were marked by circumscribing the cells with India ink. The block was pried from the slide after rapid cooling with solid CO₂, and was then trimmed and sectioned. Cells suspended in culture medium were embedded in much the same way; they were centrifuged to obtain a pellet, which was fixed, dehydrated, and infiltrated. A small fragment of the pellet with a little resin was placed on a microscope slide, where the cells were dissociated under a dissecting microscope at ca. 100 × magnification. Individual cells were then picked up with tungsten needles and transferred to droplets of resin on a carbon-coated slide. The subsequent steps were similar to those described for the staminate hairs. Pieces of tissue in the 50-500 μ range were also handled by the foregoing technique. However, after infiltration they were put into large drops of resin on a slide coated with silicone mold-release rather than on a surface coated with carbon.     

Some cybernetic aspects of early leaf growth

An analysis of photosynthesis for a leaf treated as a control system was carried out. Some similarities between selected functions of the leaf and certain mechanical and hydraulic processes were discussed, and on this basis a leaf analog and its mathematical model were elaborated. Properties of the model, which can be treated as a mathematical model for the growth of a young leaf or a young plant in comfortable conditions, were worked out with the help of automatic control theory. The theoretical results obtained were compared with experimental results for lettuce cultivated in a greenhouse.     

Use of a computer to assay motility in bacteria

An assay was developed to study the movement of free-swimming Escherichia coli. Cells were videotaped through a microscope, and the videotape images were then digitized and analyzed with a computer. Angular and linear speeds were measured for wild-type E. coli and for a smooth and a tumbly mutant. The average angular and linear speeds of a population were directly and inversely proportional, respectively, to the time spent tumbling. Changes in angular and linear speeds were followed during the response of wild-type E. coli to attractant or repellent.     

Properties of a spherical stratified gas discharge

Experimental data are obtained on the conditions for the stratification of spherical direct-current discharges and on the properties of the strata. The experiments were aimed at studying discharges in both molecular and inert gases at low pressures and were carried out with a steel chamber whose wall served as a cathode. An anode was placed at the center of the chamber. The discharge stratification was observed to be especially pronounced in media containing a small admixture of the vapor of a high-molecular substance (e.g., acetone). In discharges in pure inert gases, no strata were observed. The current-voltage characteristics of discharges at different pressures were obtained. The discharges were found to be unsteady: current pulses with a duration of about 1 microsecond and a characteristic repetition rate of about 1 kHz were detected against a steady current background and were found to correlate with the pulses of the integral emission from the discharge. The radius of each of the strata was determined as a function of its number and of the gas pressure and discharge current. The radial profiles of the time-averaged floating potential were measured in experiments with stratified discharges and with uniform discharges in argon.