Dramatic changes to well-known places go unnoticed

How well do we know our city? It turns out, much more poorly than we might imagine. We used declarative memory and eye-tracking techniques to examine people's ability to detect modifications to real-world landmarks and scenes in Toronto locales with which they have had extensive experience. Participants were poor at identifying which scenes contained altered landmarks, whether the modification was to the landmarks' relative size, internal features, or relation to surrounding context. To determine whether an indirect measure would prove more sensitive, we tracked eye movements during viewing. Changes in overall visual exploration, but not to specific regions of change, were related to participants' explicit endorsement of scenes as modified. These results support the contention that very familiar landmarks are represented at a global or gist level, but not local or fine-grained, level. These findings offer a unified view of memory for gist across verbal and spatial domains, and across recent and remote memory, with implications for hippocampal-neocortical interactions.

In vitro control of fasciation in proliferating nucellar embryos of Mangifera indica L. var totapari red small for cloning

Nucellar tissue contained in ovular halves of young fruits of Mangifera indica L. totapari red small, a dwarfing rootstock, differentiated fasciated embryonal structures in presence of 6-benzylaminopurine [BAP(0.15 mg l(-1))], 6-(gamma-gamma-dimethylallylamino) purine [2iP(0.15 mg l(-1))] and indole-3-acetic acid [(IAA(0.5 mg l(-1))] incorporated in the semisolid medium during 50-60 days. Due to embryonal fasciation, hardly 2-3 well-formed embryos could be obtained per culture of proliferating embryos. Of the 3 ethylene inhibitors [L-alpha-(2-aminoethoxyvinyl)-glycine-HCl (AVG), AgNO3 and salicylic acid (SA)] used, embryonal fasciation and necrosis of intervening tissue was completely controlled by 3-4 subcultures of fasciated mass of embryos under the influence of AVG (0.05 mg l(-1)) in presence of adenine sulphate [AdS (50 mg l(-1))] incorporated in the same medium. Almost synchronized development of isolated embryos, measuring ca 2 cm in length, was observed in a different medium used in liquid stationary state and supplemented, particularly with stress-producing substances [abscisic acid (ABA, 0.01 mg l(-1)); and polyethylene glycol (PEG, 100 mg l(-1))] besides certain other modifications. About 34% convertibility of processed embryos was obtained during a period of 90 days. The plantlets had well-developed roots along with laterals which were longer than leafy shoots. In vitro raised plants survived ex vitro for about 2 months.

Citrus tissue culture employing vegetative explants

Citrus being a number one fruit of the world due to its high nutritional value, huge production of fruits and fruit products, the citrus industry may be considered a major fruit industry. Though citrus orchard area in India is comparable to USA, the produce is far less, while its export is nil. Biotechnology has played an outstanding role in boosting the citrus industry, e.g., in Spain, which is now the biggest exporter of citrus fruit with the application of micrografting. Amongst the fruit trees, perhaps the maximum tissue culture research has been done in citrus during the past four decades, however, the results of practical value are meagre. The shortfalls in citrus tissue culture research and some advancements made in this direction along with bright prospects are highlighted, restricting the review to vegetative explants only. Whilst utilization of nucellar embryogenesis is limited to rootstocks, the other aspects, like, regeneration and proliferation of shoot meristems measuring 200 microm in length--a global breakthrough--of two commercially important scion species, Citrus aurantifolia and C. sinensis and an important rootstock, C. limonia, improvement of micrografting technique, cloning of the same two scion species as well as some Indian rootstock species, employing nodal stem segments of mature trees, of immense practical value have been elaborated. A rare phenomenon of shift in the morphogenetic pattern of differentiation from shoot bud differentiation to embryoid formation occurred during the long-term culture of stem callus of C. grandis. Stem callus-regenerated plants of C. aurantifolia, C. sinensis and C. grandis showed variation in their ploidy levels and a somaclonal variant of C. sinensis, which produced seedless fruits was isolated. Tailoring of rooting in microshoots to a tap root-like system by changing the inorganic salt composition of the rooting medium, resulting in 100% transplant success, and germplasm preservation through normal growth culture of shoots of C grandis without loss of regeneration capacity during 31 years, observed so far, are some other significant results. Plants of C. aurantifolia and C. sinensis raised from shoot meristem and micrografting were grown in a nethouse and those from nodal stem segments in the field along with the in vitro-raised plants of rootstocks, namely, C. jambhiri, C. karna and C. limonia. All the plants showed normal healthy growth. Significantly enough, the meristem regenerated plants of C. aurantifolia attained the reproductive phase just in 1 year of transplantation to soil similar to those raised from nodal stem segments of mature trees, which also produced normal fruits in the subsequent year while growing under field conditions. Thus, a significant fundamental concept of a maturity factor, carried over through as small a shoot meristem as 200 microm in length to cloned plants has been demonstrated. The concept is of far-reaching significance in citrus industry besides production of pathogen-free orchards.

In vitro high frequency regeneration of plantlets of Vigna mungo and their ex vitro growth

Of the five explants of V. mungo var. T9 used, the excised shoot tips gave best response with regard to offshoot formation followed by the embryonal axis explants. While a treatment comprising 0.5 mgL(-1) BAP, 0.5 mgL(-1) 2iP and 0.1 mgL(-1) NAA induced differentiation of an average 10 offshoots in shoot tip explants, only 3 offshoots were formed in the explants of embryonal axis in a treatment containing 0.5 mgL(-1) BAP and 0.1 mgL(-1) NAA, found optimum for them. Multiple shoots differentiated when explants with earlier regenerated and growing offshoots were first cultured in a treatment containing 0.1 mgL(-1) BAP, 0.25 mgL(-1) IAA and 5 mgL(-1) CCC and then subcultured in the same treatment but having only 1 mgL(-1) CCC. The isolated shoots rooted in 0.5 mgL(-1) IAA resulted in the formation of complete plantlets of an average height of 15 cm in 20 days. The in vitro-regenerated plants grew normally under field conditions and came to flowering as well.

Regional heterogeneity in intracellular distribution of superoxide and hydrogen peroxide within the sperm and its relation to sperm development

This study was performed to understand the regional distribution of superoxide anion radicals and hydrogen peroxide within the spermatozoa of mice during both normal and altered situations of epididymal maturation. The intracellular O2*- levels were probed employing dichlorodihydrofluorescein diacetate (DDF) as a reporter. The testicular spermatozoa from normal animals showed strong regional heterogeneity in the DDF fluorescence patterns over the various domains. Vasectomy resulted in strong inhibition in the O2* levels of spermatozoa at all stages of maturation. Interestingly, the fluorescein diacetate staining pattern was strong in the head of spermatozoa from the testis, caput, corpus, and cauda region. Further. there was a progressive reduction in the fluorescence in the head region in the spermatozoa toward the cauda region. The midpiece and tail showed moderate fluorescence, which also diminished as the spermatozoa matured. The spermatozoa from the vas deferens exhibited a weak fluorescence over the head domain, with the other domain staining extremely weak. Here again, vasectomy introduced considerable loss in the fluorescence intensity. The implications of programmed production of reactive oxygen species in specific domains of the spermatozoa during various stages of development are discussed.

A novel approach to study antibacterial properties of volatile components of selected Indian medicinal herbs

The aromatic substances of natural origin are used medicinally in Ayurveda, and can have diverse bio-dynamic actions. The existing methods like agar-cup method or disc diffusion method are not adequate to study the exclusive antibacterial effects of the volatile components of aromatic oils due to lack of ideal diffusion and evaporation from the surface. Hence an attempt is made to develop a novel approach to assess the antibacterial activity of few aromatic herbs like Eugenia caryophyllus, Thymus vulgaris, Cinnamonum zeylanium, Cuminum cyminum; these were extracted with hexane filled in tiny sterile tubes and the volatile components were tested for their antibacterial properties using standard strains of gram +ve and gram -ve bacteria grown on agar slants. The results are expressed as a percent of inhibition of the area on the slants, from the top of the extract tube. Of the four herbs selected, volatile components of Thymus vulgaris were most effective againsts all the seven test organisms.

Establishing the threshold prior to single and multiple stimulus supra-threshold strategies

The purpose of this study was to establish whether the routines used to establish the threshold at the beginning of single and multiple stimulus supra-threshold strategies yield the same values and whether data from one strategy can, therefore, be compared with those from the other without having to compensate for a difference in test intensities. Single stimulus and multiple stimulus supra-threshold strategies were conducted on 79 subjects using a Henson 4000 perimeter. On average the multiple stimulus strategy gave a value 0.095 dB higher than the single stimulus strategy. The differences between the two strategies was so small that results from the two strategies can be compared without having to compensate for any changes in the supra-threshold test intensity.