Production and particle characterization of the frustules of Cyclotella cryptica in comparison with siliceous earth

Diatoms are photoautotrophic micro-organisms that use inorganic carbon sources and light in photosynthesis. Diatom frustules were characterized in terms of particle techniques and compared with siliceous earth, i.e. depositions of diatoms that have wide technical applications. To obtain enough biomass for frustule characterization Cyclotella cryptica has been cultivated in a 15 l photobioreactor under controlled conditions. Native diatom frustules are characterized by a 1.5-fold lower density and 80-fold higher specific surface than siliceous earth. Therefore, native diatom frustules provides a material with novel properties which might be interesting for special technical application.     

滇南热区光萼猪屎豆的栽培及其利用研究

本文探讨了光萼猪屎豆(Crotalaria usaramoensis Baker.f.)在滇南热区的裁培及其利用。试验中系统地观测了光萼猪屎豆在滇南热区的生长发育特性和生物学产量以及利用情况。研究结果表明,光萼猪屎豆具有适应性广,生长快,产草量高,根瘤多以及产粒多,繁殖系数大等特点。它系一种具有多用途的优良绿肥作物,对培肥土壤,控制杂草生长均有明显的效果,是建立良好的热带农业生态系统的重要途径,是改革现行不合理的刀耕火种游耕制,实现合理轮作的有效措施,所以值得在滇南热区大力推广。     

Ligational behavior of a novel biologically active donor toward Cu(II) and Ni(II) ions and potentiation of its antibacterial activity by chelation with metal ions

The chelating behavior of a new multidentate ligand with tuberculostatic activity toward Cu(II) and Ni(II) ions has been studied. This ligand 3-(2-carboxyhydrazine)phenylimino-2-oximobutane(H2C POB) is found to chelate the above metal ions in both its keto and enol forms. The probable structures of all the complexes and the location of the bonding sites have been established through magnetic and spectroscopic (infrared, electronic) studies. The Cu(II) complex of the enol form exhibits subnormal magnetic moment at room temperature, indicating the probable existence of some sort of super exchange phenomenon in the system. The ligand itself and a few of its Cu(II) complexes have been found to exert powerful in vitro antibacterial activity toward some tuberculosis mycobacteria, such as Mycobacterium flae, Mycobacterium smegmatis, and Mycobacterium H37Rv.     

Taenia crassiceps: effect of normal and immune serum on metacestodes in vitro.

The effect of normal and immune serum on Taenia crassiceps larvae in vitro was assessed by Evans blue dye uptake and electron microscopy. Normal guinea pig, rabbit, goat, and fetal calf serum did not have any significant detrimental effects upon the larvae after 7 days of culture in vitro. Culture for 7 days in normal mouse serum resulted in some loss of tegumental microtriches but the tegument itself remained intact. Culture in hyperimmune rabbit serum resulted in complete loss of the tegument and disruption of subtegumental structures within 48 hr. The effects of immune mouse serum in vitro closely paralleled those previously seen during early immune damage in vivo. Immune serum taken 2 to 4 weeks after secondary intraperitoneal infection with T. crassiceps metacestodes caused loss of the larval tegument and degeneration of the subtegumental tissues after 7 days in culture, whereas immune mouse serum taken 6 weeks after secondary infection caused only minor ultrastructural changes and appeared to be less toxic to larvae than normal mouse serum. Although complement appeared to increase the number and severity of the tegumental lesions, the presence of heat-labile components of complement was not essential for mediation of tegumental damage by immune mouse serum.     

Toxoplasma gondii: purification of trophozoites propagated in cell culture.

A new procedure is described for the purification of trophozoites from the virulent RH strain of Toxoplasma gondii propagated in baby hamster kidney (BHK-21) cell cultures. The culture medium containing host cell debris and trophozoites was filtered through glass-wool filtering fiber, which removed most host cell material. The filtrate containing trophozoites was centrifuged, and the trophozoite pellet was resuspended and washed in phosphate-buffered saline. An average of about 75% of the original number of trophozoites was recovered. No loss of trophozoite viability was observed as determined by the rate of host cell culture monolayer destruction. The amount of host cell material contamination in the final trophozoite fraction was negligible as determined by measuring radioactivity in the trophozoite fraction after cofiltration with noninfected host cell material which had been prelabeled with radioactive precursors.     

The compound internal pyrenoid in cultured cells of the green algaMonoraphidium griffithii (Berkel.) Komar.-Legner.

Summary The chloroplast ultrastructure ofMonoraphidium griffithii (Berkel.) Komar.-Legner. has been studied in axenic cultures of various ages. The algae have grown in a complete nutrient solution (illumination about 3,000 lx) and on its agar medium (illumination about 600 lx).The large parietal cup-shaped chloroplast of the cells includes a multiformed compound internal pyrenoid that is situated, especially in older cells, in the central part of the chloroplast opposite to the dictyosome and the nucleus. The chloroplast thylakoids either reach the edge of the pyrenoid or penetrate its matrix and run there parallel in more or less long bits. Starch grains were not found to form any sheath around the pyrenoid regions. The number of starch grains increased with the age of the cell.     

Schistosoma mansoni: axenic culture of daughter sporocysts

Daughter sporocysts of Schistosoma mansoni were cultured axenically for up to 13 days in media conditioned with Aedes albopictus tissue cultures. Sporocysts increased in length, processes appeared on the tegument, and small embryos developed. Two media, differing in ionic balance and source of amino nitrogen, were compared. No development occurred in either medium when freshly prepared.     

Schistosoma mansoni: emergence of progeny-daughter sporocysts in monoxenic culture

Daughter sporocysts of Schistosoma mansoni released from mother sporocysts from Biomphalaria glabrata were cultured monoxenically for 21 days at 27.4 C in a medium consisting of a balanced salt-sugar solution supplemented with lactalbumin hydrolysate, inactivated fetal calf serum, serum Fraction A, and egg ultrafiltrate. The sporocysts were retained in transparent porous membranes so that their germinal development could be observed without interference from the underlying cells of Aedcs albopictus tissue cultures; the membrane permitted interchange of medium between sporocysts and cell cultures. The greatest increase in length, fivefold, occurred by 18 days. Progeny-daughters began to emerge at 9 days.The effects of pH, osmolality, and antibiotics were evaluated in axenizing solutions. Optimal conditions were a pH range of 6.5–7.6 and 113–153 mOsm. Antibiotics were not toxic.     

Leishmania mexicana: Serial cultivation of intracellular stages in a cell-free medium

A cell-free liquid medium has been devised for serial cultivation of Leishmania mexicana pifanoi amastigotes at 33 and 35 C. It consists of tissue culture Medium 199 fortified primarily with a high concentration of water-soluble vitamins, nucleotides, and inactivated fetal bovine serum. The initial pH of the medium is 7.2. Starting with a population of promastigotes as inoculum and serially cultured at 33 or 35 C at 4- to 10-day intervals, the proportion of amastigotes steadily increased and that of promastigotes gradually decreased during the first subculture. By the end of the incubation period in the second subculture, practically all (99%) of the organisms are amastigotes. The amastigotes thus obtained can be cultured indefinitely by serial transfers. In this medium, amastigotes may reach a density of 8 × 10⁷/ml after 10 days of incubation at 33 C, and 5 × 10⁷/ml at 35 C. The medium was modified to have an initial pH of 8.0 by Hepes [4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid] buffer and higher concentrations of sodium bicarbonate. When amastigotes cultured in the original medium at 33 or 35 C are transferred into the modified medium and incubated at 26 C, the amastigotes entirely transformed into promastigotes after three serial passages. These promastigotes could be serially subcultured indefinitely in the modified medium at 4- to 12-day intervals. The promastigotes cultured at 26 C may reach a population density of 7 × 10⁷/ml after 12 days of incubation.     

Giardia lamblia: autoradiographic analysis of nuclear replication

Giardia lamblia trophozoites, grown in axenic culture, were labeled for various periods of time with [3H]thymidine. After autoradiography, grains were counted over each of the two nuclei in each trophozoite. Analysis of the fraction of trophozoites labeled for each time period resulted in an estimate of a generation time of 15 hr. The DNA synthetic or S phase for a trophozoite in culture was calculated to be 1.8 hr. G1 and G2 periods were determined to be 8.5 and 3 hr, respectively. A comparison of the labeling density between the two nuclei indicated that replication takes place simultaneously in both nuclei for at least 70% of S period. The fraction of asymmetrically labeled trophozoites is consistent with a model in which the nuclei replicate out of phase by 15-30 min, but, due to the small diameter of the nuclei relative to the grain size, the possibility that replication takes place simultaneously in both nuclei of a trophozoite throughout the S phase cannot be ruled out.