A new species of Bradyidius (Copepoda, Calanoida) from the Gulf of Carpentaria, Australia

A new species of copepod belonging to the family Aetideidae,Bradyidius slyliformis sp. nov. is described and figured. Therelationship of this species to the other 12 members of thegenus is discussed. ¹Present address: 121 Jalan Athinahapan Dua, Taman Tun Dr Ismail,60000 Kuala Lumpur, Malaysia     

Effect of high concentration of nutrients onBacillus thuringiensis cultures

Summary Bacterial insecticide production using a strain ofBacillus thuringiensis var. kurstaki was studied in batch culture considering the influence of increasing concentration of components of a glucose — yeast extract — mineral salts medium.It was found that spore counts were increased from 1.08×10¹² spores. 1^–1 to 7.36×10¹² spores. 1^–1 and toxin level from 1.05 mg.ml^–1 to 6.85 mg.ml^–1, when the concentration of glucose was increased from 8 to 56 (g 1^–1), with the corresponding increase in the rest of medium components. Higher concentration of nutrients inhibit either spore count or toxin production.Preliminary experiments of fed-batch cultures which allows the use of high amounts of nutrients were also carried out. In this case spore counts of 1.2×10¹³ spores.1^–1 were achieved.     

Structure of a protein catalyzing the formation of 11 cis-retinal in the visual cycle of invertebrate eyes

A pigment made up of a protein able to bind retinal as well as retinol is described. The molecule consists of a dimer with a molecular weight of 50,000 which binds one molecule of retinal. The binding site for retinal is a Schiff base buried in the interior of the protein. Retinol is probably bound to the protein in the same site as for retinal, although not covalently, as suggested by the absorbance spectra. The protein, extracted from honeybee retina, is involved in visual pigment metabolism, and its structure may elucidate the mechanism of the stereospecific photoisomerization of all trans-retinal to 11-cis-retinal.     

Pheophytin-mediated energy storage of photosystem II particles detected by photoacoustic spectroscopy

The photoacoustic (PA) characteristics (energy storage and heat dissipation) of photosystem II (PSII) core-enriched particles from barley were studied (i) in conditions where there was electron flow, i.e., in the presence of a combination of the electron acceptor K₃ Fe (CN)₆, referred to as FeCN, and the electron donor diphenylcarbazide (DPC), and (ii) in conditions where electron flow was suppressed, i.e., in the absence of FeCN and DPC. The experimental data show that a decrease of heat dissipation with a minimum at 540 nm can be interpreted as energy storage resulting from the presence of pheophytin (Pheo) in the PSII particles. On account of the capability of the PA method to measure the energy absorbed by the chromophores which is converted to heat, it is suggested that the PA detection of Pheo present in the PSII complex will permit to clarify the function of processes involving non-radiative relaxation of excited states in P680-Pheo-Q_A interactions.Abbreviations -Car -Carotene - Chl Chlorophyll - DPC Diphenylcarbazide - EPR Electron Paramagnetic Resonance - FeCN potassium ferricyanide - HEPES N-2-hydroxyethylenepiperazine-N-2-ethanesulfonate - P680 reaction center of PSII - PA Photoacoustic - Pheo pheophytin - PSI photosystem I - PSII photosystem II - Q_A primary electron acceptor of PSII     

Investigations on circumferential microfilament bundles in rat retinal pigment epithelium

The presence of contractile proteins in normal rat retinal pigment epithelium has been studied using fluorescence and electron microscopy. Investigations using the F-actin binding toxin, phallacidin, coupled to the fluorochrome nitrobenzoxadiazole, revealed a band of fluorescence at or near the cell membrane. Immunofluorescent observations with anti-myosin and anti-alpha-actinin antisera gave similar results. Electron microscopy employing glutaraldehyde-8% tannic acid fixation revealed the presence of a circumferential microfilament band beneath the pigment epithelial apical surface that is closely associated with the plasma membrane and junctional complexes. Freeze-fracture studies confirmed the relationship of this band to the junctional complexes. The microfilament band measures approximately 0.5 micron +/- 0.2 micron in width and is composed of numerous 6 to 7 nm filaments. Some microtubules are seen in regions around the band, but no organelles appear to be associated with this structure. In en face sections through the zonula adherens, the circumferential microfilament band is associated with 30-nm electron-dense particles that are bound to the internal side of the membrane. Morphological evidence suggests that these may serve in anchoring the band to the membrane and assist in aligning the microfilament bands of adjoining cells. In the subapical cytoplasm, a microfilament bundle network was detected that interfaced with the circumferential microfilament band. In some cases, pigment epithelium was incubated in media-199 containing 25 to 50 ng/ml phallacidin prior to fixation. Circumferential microfilament bands of tissues treated in this manner exhibited a striated appearance.     

Temperature regulation in a burrow-nesting tropical seabird,the Wedge-tailed Shearwater (Puffinus pacificus)

Summary At low air temperatures (2.3–13.9°C), Wedge-tailed Shearwaters (Puffinus pacificus) shivered and their oxygen consumption increased to as much as 283% of the mean value (0.77 ml O₂/g·h) within the thermoneutral zone of air temperature (23–34°C). The minimal thermal conductance of the tissues and plumage was similar to the value predicted from the body mass (320.5 g). The oxygen consumption of the birds within their thermoneutral zone was lower than predictions based on body mass. At elevated air temperatures, the shearwaters panted at respiratory frequencies as high as 260 respirations/min; maximal respiratory frequencies were not invoked until the birds had become hyperthermic. During exposure to a hot environment, the oxygen consumption of the birds increased and in most instances the shearwaters were not able to lose heat equivalent to their concurrent metabolic heat production.Symbols and abbreviations BMR basal metabolic rate - C _total total thermal conductance - f respiratory frequency - TEWL total evaporative water loss - T _st stomach temperature - T _re rectal temperature     

Transforming potential of a myc-containing variant of feline leukemia virus in vitro in early-passage feline cells.

We studied a naturally occurring variant of feline leukemia virus (FeLV) in which the oncogene myc has substituted for a portion of the viral structural genes (myc-FeLV). myc-FeLV was rescued by replication in the presence of FeLV as helper, and its biological activity was examined in early-passage feline cells in vitro. Infection of leukocytes from peripheral blood, spleen, or thymus, or of kitten fibroblasts did not immortalize these cells or alter them morphologically. Northern blot (RNA blot) analysis of virion RNA prepared from the supernatant of infected cells demonstrated the 8.2-kilobase genome of FeLV, but did not demonstrate the 5.0-kilobase genome of myc-FeLV. Apparently, the myc-FeLV genome was lost in the absence of the selective pressure of transformation. In contrast, infection of embryonic fibroblasts with myc-FeLV(FeLV) rendered these cells capable of greatly increased, if not infinite, proliferative potential. The cells were morphologically altered compared with controls and were only loosely adherent to the substrate. The cells failed to proliferate in semisolid medium and did not form tumors when inoculated subcutaneously into athymic mice. Blot analyses demonstrated the presence and expression of integrated proviral DNAs of both FeLV and myc-FeLV in these cells. They appear, then, to represent cells partially transformed by infection with myc-FeLV(FeLV). The action of feline v-myc in early-passage cells in vitro was compared to that of avian v-myc.     

The association between spontaneous pyelonephritis and maturity-onset diabetes mellitus in male MM mice

Blood glucose and glucose tolerance tests demonstrated that many male MM mice are diabetic. Serial urine sampling showed that the diabetes occurred only in mature MM males and consisted of a single self-limiting episode. Histological examination of the pancreas, together with measurements of body weight, glycosylated haemoglobin and plasma insulin, revealed that the diabetes was of the maturity-onset insulin-resistant type. Bacteriological examination of the urine samples showed that urinary tract infection, a known feature of male MM mice, occurred in the diabetics but only after the onset of hyperglucosuria. It was concluded that the high urinary glucose levels of diabetic MM males are of prime importance in the aetiology of the renal infection which occurs rarely in non-diabetic MM males or in other strains in the colony. An infectious aetiology for the diabetes per se was excluded by the existence of diabetes in germfree MM males.     

Antitrypanosomal action of cis-diamminedichloroplatinum (II) analogs

The present report deals with the alterations produced by cis-diamminedichloroplatinum (II) (DDP), and 2 of its analogs: cis-Pt(II)(tranylcypromine)2Cl2 and cis-Pt(II)(benzothiazole)2Cl2 in cultured epimastigote forms of Trypanosoma cruzi. Studies have been performed at the ultrastructural level and the inhibitory effect of these complexes on macromolecule synthesis, evaluated by 3H-thymidine, 3H-uridine, and 3H-leucine incorporation, has been investigated. DDP at concentrations of 50 and 100 micrograms/ml does not inhibit significantly the incorporation of radioactive precursors, but a clear decrease was observed with the 2 analogs. Eight hours of treatment at a concentration of 10 micrograms/ml rendered in all 3 cases an increase in autophagic vacuoles and lipids as well as an abnormal condensation of the nucleus chromatin.