Promotion of indole alkaloid production in Catharanthus roseus cell cultures by rare earth elements

Production of the indole alkaloids, ajmalicine or catharanthine, in cell suspension cultures of Catharanthus roseus was enhanced by cerium (CeO₂ and CeCl₃), yttrium (Y₂O₃) and neodymium (NdCl₃). The yield of ajmalicine in these treated-cultures reached 51 mg l^–1 (CeO₂), 40 mg l^–1 (CeCl₃), 41 mg l^–1 (Y₂O₃) and 49 mg l^–1 (NdCl₃) while catharanthine production reached to 36 mg l^–1 (CeO₂) and 31 mg l^–1 (CeCl₃). A major portion of increased alkaloids was released into medium in these treatments. But Sm₂O₃, SmCl₃, La₂O₃, LaCl₃, complex of chromium (III)-titanium (IV) and NaSeO₄ treatments had little effect on alkaloid production of C. roseus cell cultures.     

Biological responses of tight junction to ionizing radiation and electromagnetic field expostion.

The tight junctions form and regulate the paracellular barrier in the intercellular spaces between epithelial and endothelial cells. They play important roles in the cellular and pathological processes, which follow exposure to radiation. Therefore, analysis of their changes upon different kind of irradiation may help to understand the basic events governing their function and give important information for the radiobiological research and clinical practice as well. The immunohistochemical data on the distribution of occludin presented here demonstrate the breakdown of tight junctions in Madin Darby kidney cells exposed to ionizing irradiation and show, on the other hand that magnetic field exposures upon 100 microT leave the occludin staining pattern intact.     

Experimentally induced helper dispersal in colonially breeding cooperative cichlids

The ‘benefits of philopatry’ hypothesis states that helpers in cooperatively breeding species derive higher benefits from remaining home, instead of dispersing and attempting to breed independently. We tested experimentally whether dispersal options influence dispersal propensity in the cooperatively breeding Lake Tanganyika cichlids Neolamprologus pulcher and N. savoryi. Cooperative groups of these fishes breed in densely packed colonies, surrounded by unoccupied, but apparently suitable breeding habitat. Breeding inside colonies and living in groups seems to benefit individuals, for example by early detection and deterrence of predators. We show that despite a slight preference of both species for habitat with a higher stone cover, 40% of the preferred habitat remained unoccupied. On average, the colonies contained a higher number of (1) predators of adults, juveniles and eggs, (2) shelter competitors, and (3) other species including potential food competitors, compared to the outside colony habitat. Apparently, habitat differences cannot explain why these cichlids breed in colonies. Accordingly, dispersal may not be limited by a lack of suitable breeding shelters, but by the relatively higher risk of establishing an outside- compared to a within-colony breeding territory. To test whether cichlids prefer within- to outside-colony breeding territories, we provided breeding shelters inside the colony and at the colony edge and studied helper dispersal. As expected, significantly more shelters were occupied within the colony compared to the edge. New breeding pairs with several helpers occupied these shelters. We conclude that although breeding habitat is plentiful outside the colonies, helpers delay dispersal to obtain a higher quality breeding position within the group or colony eventually, or they disperse in groups. Our results suggest that (1) group augmentation and Allee effects are generally important for dispersal decisions in cooperatively breeding cichlids, consistent with the ‘benefits of philopatry hypothesis’, and (2) habitat saturation cannot fully explain delayed dispersal in these species.     

Synthesis and in vitro activity of dicationic bis-benzimidazoles as a new class of anti-MRSA and anti-VRE agents

A new class of novel bis-benzimidazole diamidine compounds have been synthesized and evaluated for in vitro antibacterial activities, including drug-resistant bacterial strains. Anti-MRSA and anti-VRE activities of the most potent compound 1 were more active than Vancomycin. The mechanism of action for this class of compounds appears to be different from existing antibiotics. Bis-benzimidazole diamidine compounds have potential for further investigation as a new class of potent anti-MRSA and anti-VRE agents.     

Studies of the slowing of the dienone-phenol rearrangement of a steroidal 1,4-dien-3-one by the introduction of an 11-keto group

It has been shown previously that steroidal 11-keto-1,4-dien-3-ones undergo dienone-phenol rearrangement significantly more slowly than their 11-deoxy-, or 11 beta-hydroxy- and 11-acetoxy analogs. We have tested the explanations suggested for this, and are able to reject most of them. There remains the probability that the 11-keto group reduces the migrating ability of the adjacent atom, C-9, which frequently migrates in steroidal rearrangements.