The dark-colour-inducing neurohormone of locusts in relation to an albino mutant of Schistocerca gregaria

In the albino mutant of an Okinawa strain of Locusta migratoria (L.) (Orthoptera: Acrididae), albinism is caused by the absence of the dark‐colour‐inducing neurohormone (DCIN), which is present in the corpora cardiaca (CC) of normally coloured phenotypes. This study tests whether the absence of DCIN is responsible for albinism in an albino mutant of another locust, Schistocerca gregaria (Forsk.) (Orthoptera: Acrididae). This seemed feasible because a single Mendelian unit controls albinism in both species. However, implantation of CC, or injection of an extract of CC, from albino donors of S. gregaria, induce dark coloration in crowded nymph recipients of the Okinawa albino mutant of L. migratoria, as effectively as do implanted CC, or injections of extract of CC, from normal phenotype donors of S. gregaria. Therefore, DCIN is present in the albino mutant of S. gregaria, and consequently, the albinism in this mutant is not caused by its absence. Implantation of CC, or injection of extracts of CC, from albino donors of S. gregaria to conspecific albino nymphs does not induce darkening. Only extremely high doses of synthetic DCIN injected into albino nymphs of S. gregaria are effective, inducing some darkening. The dose to induce such darkening in albino nymphs of S. gregaria is 50 nmol, ≈ 5 × 10⁶ times higher than that (10 femtomol) needed to induce equivalent darkening in nymphs of the Okinawa albinos of L. migratoria. The results are discussed and some possible explanations of the observed effects outlined.     

Antiepileptic effects of amphetamine may require GABA (benzodiazepine) activity

Secondary components of visual evoked potentials (slow negative wave-SNW, and photically-evoked sensory afterdischarge-SAD) are known to be precursors of experimentally activated wave-spike discharges, similar to wave-spikes of petit mal epilepsy. Both SNW and SAD may be potently suppressed wither by amphetamine or GABAergic compounds such as diazepam and sodium valproate. A hypothesis was tested in the present study, that amphetamine-induced suppression of wave-spike discharges may require GABA-benzodiazepine activity for its expression.Electrocortical activity was recorded and averaged in unrestrained albino rats with chronically implanted epicortical electrodes. SNW and SAD obtained in habituated rats in the predrug state were potently suppressed by amphetamine (1 mg/kg, i.p.). Fifteen minutes after amphetamine injection, a challenging drug (metrazol, picrotoxin, convulsant benzodiazepine, Ro 5-3663, or imidazodiazepine, Ro 15-1788) was administered intraperitoneally. Subconvulsive doses of metrazol (10 mg/kg) reversed amphetamine suppression; imidazodiazepine (20 mg/kg) and picrotoxin (1.5 mg/kg) reliably opposed the SNW suppression; convulsant benzodiazepine, Ro 5-3663 (2 mg/kg), showed modest and nonsignificant effect in the same direction. It is proposed that the antiepileptic potency of amphetamine may be associated with its ability, apparently via modulatory effect of norepinephrine, to facilitate the activation of benzodiazepine-GABA receptors.     

Limestone gravel as growth medium in hydroponics

Summary Plants were grown in gravel beds of basalt or limestone. With the standard nutrient solution yields for the plants grown in the limestone gravel were very much reduced and the plants were chlorotic. This chlorosis and reduced yields remained even if the gravel was acid or water washed beforehand, or if it was pretreated in high phosphate concentrations.High yields, comparable to those obtained in basalt beds were obtained if phosphate and iron were added in small amounts (0.1mM P, 1 mg/1 Fe) at each irrigation. This technique to avoid lime induced chlorosis can be easily and economically accomplished in hydroponics. It proved successful here with lettuce, cucumber, tomato and eggplants.     

Antibody Response of Animals to Mycoplasma pneumoniae Measured by Latex Agglutination

The standardization, application, and usefulness of latex agglutination for Mycoplasma pneumoniae antibody titration were investigated and compared with tetrazolium reduction inhibition and complement fixation. The sera of guinea pigs and monkeys reacted in a specific fashion, whereas rabbit serum required pretreatment to eliminate its nonspecific agglutinin. Human serum given such pretreatment still contained a nonspecific agglutinin. The latex agglutination procedure compared favorably with complement fixation and metabolic inhibition tests for evaluating vaccine antigenicity.     

Titration and Neutralization of Poliovirus in Micro Tissue Culture Under Increased Carbon Dioxide

Modification of the micro tissue culture technique, including incubation under increased CO(2), resulted in prolongation of the viability of the cells. As a consequence, satisfactory titrations of poliovirus and of poliovirus antiserum have been achieved by the micro method. The technique offers a number of advantages over conventional methods.     

Unresponsiveness of rat peritoneal mast cells to immunologic reactivation.

Rat peritoneal mast cells cocultured with 3T3 fibroblasts (MC/3T3) were activated with Ag or with anti-IgE antibodies in the presence of Ca2+, and their responsiveness to a second similar challenge was evaluated. MC/3T3 were presensitized with IgE anti-DNP antibodies and activated with DNP-human serum albumin. When these MC/3T3 were reactivated with the same Ag 2 and 6 h later, they released only a minimal percentage of histamine. A gradual recovery of responsiveness was detected during the first 7 days after activation, and a full recovery was attained by days 14 to 21. A similar pattern of unresponsiveness was observed when MC/3T3 were challenged and rechallenged with cercarial Ag after presensitization with anticercarial serum. Activation of MC/3T3 with one Ag (DNP-human serum albumin or cercarial) and rechallenge 3 days later with the other Ag did not overcome the state of partial unresponsiveness. Challenging MC/3T3 with anti-IgE led to a subsequent unresponsiveness to rechallenge with the same ligand, regardless of whether or not the cells were presensitized with IgE antibodies. Cross-linkage with anti-IgE resulted in a more intense and prolonged state of unresponsiveness in comparison with that observed with Ag. When MC/3T3 activated with anti-IgE were rechallenged with various IgE-independent agents they released a percentage of histamine comparable to that of control cultures challenged with these secretagogues for the first time. MC/3T3 partially resynthesized their histamine content during the two-week period after activation. Our results suggest that MC undergo a temporary state of "physiologic" unresponsiveness after immunologic activation in the presence of calcium ions.     

Electromyograms from radiotelemetry as indicators of reproductive activity in lake trout

One male and one female lake trout, Salvelinus namaycush , were held in a laboratory tank simulating a natural spawning environment. Their behaviour during their reproductive period was videotaped each day for 2 h at dusk. The fish activities were classified into seven types: resting, casual swimming, side-thrusting, chase, chase-nudge, body alignment, shuddering. As the reproductive period progressed the fish became more generally active with a marked increase in interactive behaviours such as pursuit of the female by the male (chasing, chasing-nudging). Around spawning time, shuddering and body alignment activity reached apeak. Each fish was equipped with an internally implanted radiotelemetry package able to detect and transmit continuously over the course of each day signals that reflect production of the electromyograms (EMGs) that accompany fish axial muscle activity (high muscular activity gives low pulse interval times in milliseconds). The lowest EMG pulse intervals corresponded with what, from the video records, appeared to be the time of highest physical activity during the reproductive period–viz. that associated with spawning activity during dusk. Other times during the diel cycles over the reproductive period, except for times of roughly similar duration during early morning (which may also be reflections of spawning) showed considerably lower muscular activity. It is concluded that transmitted EMG records could probably be used as indicators of spawning activity of lake trout in at least some of those places in the field where they cannot normally be located by visual means.     

Pseudohypoparathyroidism type Ia: two new heterozygous frameshift mutations in exons 5 and 10 of the Gsα gene

Pseudohypoparathyroidism type Ia (PHP-Ia) is a hereditary disease characterized by resistance to PTH and other hormones that act via cAMP. Patients have deficient activity of Gs, the subunit of the G protein, which couples hormone receptors to stimulation of adenylate cyclase. We describe two new mutations discovered in two sporadic patients with PHP-Ia. Using genomic DNA, we have amplified exons 2–13 of the Gs gene (GNAS1) by PCR, and sequenced the resulting products. Both patients had Albright's hereditary osteodystrophy, resistance to multiple hormones, and deficient Gs activity. In the first patient, a deletion of a C in exon 5 at codon 115 was found. In the second patient, an insertion of a C in exon 10 at codon 267 was detected. Both these heterozygous mutations cause frameshift, and predict decreased production of Gs. This report adds two new Gs mutations to the known ten mutations recently described.     

Remote sensing of chlorophyll in Lake Kinneret using highspectral-resolution radiometer and Landsat TM: spectral features of reflectance and algorithm development

High-resolution reflectance spectra in the range of 400–850nm were obtained from Lake Kinneret during a period when densepopulations of the dinoflagellate Peridinium gatunense dominatedthe phytoplankton. Chlorophyll (Chl) concentrations ranged from5.1 to 185 mg m^–3 and from 2.4 to 187.5 mg m^–3 inthe samples of two independent experiments. The most prominentfeatures of the reflectance spectra were: (i) a wide minimumfrom 400 to 500 nm; (ii) a maximum at 550–570 nm, whichdid not surpass 3% in samples with high Chl concentration (>20mgm^–3), indicating a strong absorption by pigments in thegreen range of the spectrum; (iii) a minimum at 676 nm; thiswas {small tilde}1% and was almost insensitive to variationin Chl concentration >10 mg m^–3; (iv) a maximum reflectanceshowed near 700 nm; its magnitude and position were highly dependenton chlorophyll concentration. High-spectral-resolution datawere used as a guideline for selection of the most suitablespectral bands for chlorophyll remote sensing. Models were devised,based on the calculation of the integrated area above the baselinefrom 670 to 850 nm and the reflectance maximal height withinthis range. Some algorithms already used m previous studieswere tested and showed a plausible degree of accuracy when appliedto the current data base. However, novel models devised in thisstudy improved substantially the accuracy of Chl estimationby remotely sensed data, by reducing the estimation error from>11 to 6.5 mg m^–3 Those models were validated by anindependent data set where Chl concentration ranged over twoorders of magnitude. The use of three relatively narrow spectralbands was sufficient for Chl mapping in Lake Kinneret. Therefore,a relatively simple sensor, measuring only a few bands willbe employed in future applications for Chl monitoring in inlandwaters. Radiometric data were also used to simulate radiancesin the channels of TM Landsat and to find the algorithm forChl assessment. The ratio of channel 4 to channel 3 was usedand enabled Chl estimation with an error of <15mg m^–3This algorithm was employed to map Chl in the entire area ofLake Kinneret with 10 gradations.     

Intervening sequences in the ribosomal RNA genes of Ascaris lumbricoides: DNA sequences at junctions and genomic organization

An rDNA size class in the genome of the nematode Ascaris lumbricoides is described which is interrupted by a 4.5-kb long intervening sequence located in the 26S coding region. This molecular form occurs in approximately 15 copies per haploid genome and amounts to approximately 5% of the total nuclear rDNA. Intervening sequences are present only in the 8.8-kb rDNA, but not in the 8.4-kb rDNA repeating units of A. lumbricoides. Cloning of the interrupted rDNA units revealed, in addition to the main 4.5-kb insertion, shorter intervening sequences of 4-kb and 119-bp length. Both shorter rDNA forms are present in the single copy range of the haploid genome. Sequence analyses of the intervening sequence/rDNA junctions show an identical right-hand junction for all of the three different rDNA forms. The two shorter intervening sequences are a coterminal subset of the right-hand end of the main 4.5-kb insertion, whereas all three insertions have a different left-hand junction with the coding region of rDNA. Each intervening sequence is flanked by a short direct repeat of variable length, being only once present in the uninterrupted rDNA. The intervening sequences of A. lumbricoides show striking similarity to the organization of type I insertion family in dipteran flies, even though they are inserted at different positions in the 26S coding region. Additional rDNA intervening sequences may be present outside of the rDNA cluster, but in not more than 15-20 homologous copies per haploid genome.