Pattern of Resource Allocation of Six Plantago Species with Different Breeding Systems

Plantago exhibit great deal of differences in the breeding system. The reproductive effort calculated on the basis of, (i) dry biomass of foliar and floral parts and (ii) seed output-weight (mg) per unit leaf area (cm²), exhibits relation with breeding system. The predominantly inbreeding taxa invest higher reproductive effort compared to their outbreeding allies. In terms of sex allocation strategies, the outbreeding species like P. lanceolata, P. lagopus invest more to the development of floral features and to male functions. On the contrary, inbreeding species such as P. patagonica, P. drummondii, and P. ovata invest greater resources to the female function. Received 13 April 1998/ Accepted in revised form 6 November 1998     

Airborne Pollen Grains of Gurdur,Turkey

Ｔｈｃ ｐｏｌｌｅｎ ｇｒａｉｎｓ ｉｎ ｔｈｅ ａｔｍｏｓｐｈｅｒｅ ｏｆ Ｂｕｒｄｕｒ ｈａｖｅ ｂｅｅｎ ｓｔｕｄｉｅｄ ｆｏｒ ａ ｔｗｏ－ｙｅａｒ ｐｅｒｉｏｄ（１９９６ｔｈｒｏｕｇｈ １９９７）ｗｉｔｈ ａ Ｄｕｒｈａｍ ｓａｍｐｌｅｒ．Ａ ｔｏｔａｌ ｏｆ １１ ８８１ ｐｏｌｌｅｎ ｇｒａｉｎｓ ｂｅｌｏｎｇｉｎｓ ｔｏ ３９ ｔａｘａ ｈａｖｅ ｂｅｅｎ ｉｄｅｎｔｉ－ｆｉｅｄ     

Biology and interactions of two distinct monopartite begomoviruses and betasatellites associated with radish leaf curl disease in India

Background

Emerging whitefly transmitted begomoviruses are major pathogens of vegetable and fibre crops throughout the world, particularly in tropical and sub-tropical regions. Mutation, pseudorecombination and recombination are driving forces for the emergence and evolution of new crop-infecting begomoviruses. Leaf curl disease of field grown radish plants was noticed in Varanasi and Pataudi region of northern India. We have identified and characterized two distinct monopartite begomoviruses and associated beta satellite DNA causing leaf curl disease of radish (Raphanus sativus) in India.

Results

We demonstrate that RaLCD is caused by a complex of two Old World begomoviruses and their associated betasatellites. Radish leaf curl virus-Varanasi is identified as a new recombinant species, Radish leaf curl virus (RaLCV) sharing maximum nucleotide identity of 87.7% with Tomato leaf curl Bangladesh virus-[Bangladesh:2] (Accession number AF188481) while the virus causing radish leaf curl disease-Pataudi is an isolate of Croton yellow vein mosaic virus-[India] (CYVMV-IN) (Accession number AJ507777) sharing 95.8% nucleotide identity. Further, RDP analysis revealed that the RaLCV has a hybrid genome, a putative recombinant between Euphorbia leaf curl virus and Papaya leaf curl virus. Cloned DNA of either RaLCV or CYVMV induced mild leaf curl symptoms in radish plants. However, when these clones (RaLCV or CYVMV) were individually co-inoculated with their associated cloned DNA betasatellite, symptom severity and viral DNA levels were increased in radish plants and induced typical RaLCD symptoms. To further extend these studies, we carried out an investigation of the interaction of these radish-infecting begomoviruses and their associated satellite, with two tomato infecting begomoviruses (Tomato leaf curl Gujarat virus and Tomato leaf curl New Delhi virus). Both of the tomato-infecting begomoviruses showed a contrasting and differential interaction with DNA satellites, not only in the capacity to interact with these molecules but also in the modulation of symptom phenotypes by the satellites.

Conclusion

This is the first report and experimental demonstration of Koch's postulate for begomoviruses associated with radish leaf curl disease. Further observations also provide direct evidence of lateral movement of weed infecting begomovirus in the cultivated crops and the present study also suggests that the exchange of betasatellites with other begomoviruses would create a new disease complex posing a serious threat to crop production.     

Retrovirally introduced antisense integrin RNA inhibits neuroblast migration in vivo.

We used retrovirus-mediated gene transfer to ask whether integrins are involved in the development of neuroblasts in the chicken optic tectum. Vectors were constructed with the E. coli lacZ gene in the sense orientation and beta 1 integrin sequences in the antisense orientation. Tests in culture showed that the progeny of cells infected by these vectors were identifiable by expression of LacZ and had reduced levels of beta 1 integrins on their surfaces. We then injected these vectors into optic tecta on E3, at the height of neuronal production. Clones of LacZ-positive cells were analyzed 3-9 days later, as they migrated along radial glia to form the tectal plate. Antisense sequences had little effect on the proliferation of progenitors, or on the radial stacking of their progeny in the ventricular zone (E6). However, many antisense-bearing cells accumulated in the ventricular zone and failed to migrate into the tectal plate (E7.5 and E9). At later stages (E12), few antisense-bearing cells could be found. Thus, integrin appears to be required in the migratory process, and cells that fail to engage in integrin-mediated interactions may die.     

Mucin secretion by the human colon cell line LS174T is regulated by bile salts

We recently reported that bile salts play a role in the regulation of mucin secretion by cultured dog gallbladder epithelial cells. In this study we have examined whether bile salts also influence mucin secretion by the human epithelial colon cell line LS174T. Solutions of bile salts were applied to monolayers of LS174T cells. Mucin secretion was quantified by measuring the secretion of [3H]GlcNAc labeled glycoproteins. Both unconjugated bile salts as well as taurine conjugated bile salts stimulated mucin secretion by the colon cells in a dose-dependent fashion. Hydrophobic bile salts were more potent stimulators than hydrophilic bile salts. Free (unconjugated) bile salts were more stimulatory compared with their taurine conjugated counterparts. Stimulation of mucin secretion by LS174T cells was found to occur at much lower bile salt concentrations than in the experiments with the dog gallbladder epithelial cells. The protein kinase C activators PMA and PDB had no stimulatory effect on mucin secretion. We conclude that mucin secretion by the human colon epithelial cell line LS174T is regulated by bile salts. We suggest that regulation of mucin secretion by bile salts might be a common mechanism, by which different epithelia protect themselves against the detergent action of bile salts, to which they are exposed throughout the gastrointestinal tract.