A lossless compression algorithm for DNA sequences.

The increase of the amount of DNA sequences requires efficient computational algorithms for performing sequence comparison and analysis. Standard compression algorithms are not able to compress DNA sequences because they do not consider special characteristics of DNA sequences (i.e., DNA sequences contain several approximate repeats and complimentary palindromes). Recently, new algorithms have been proposed to compress DNA sequences, often using detection of long approximate repeats. The current work proposes a Lossless Compression Algorithm (LCA), providing a new encoding method. LCA achieves a better compression ratio than that of existing DNA-oriented compression algorithms, when compared to GenCompress, DNACompress, and DNAPack.

Intralesional verapamil injection in treatment of Peyronie's disease. Preliminary results

Objective To evaluate the efficacy of intra-lesional verapamil injection in the treatment of Peyronie's disease. Patients and Methods Twenty-six patients with Peyronie's disease were divided into two groups: the verapamil treatment group (study group) including 13 patients and the saline group (control group) including another 13 patients. The patients' age ranged from 35 to 58 years with a mean age of 43.75 years. The patients in the study group were subjected to a weekly injection of 10 mg verapamil hydrochloride (5 mg / 2 ml) into the plaque for the duration of six weeks. At the same time; the patients in the control group received a weekly injection of normal saline into the plaque; also for the duration of six weeks. The patients' response to the injections was evaluated subjectively with respect to pain and sexual dysfunction and objectively with respect to the plaque volume and the degree of curvature. Results Following therapy; pain was improved in 8 of 9 patients (88.9) of the patients in the verapamil group; while in the control group it was stationary in 6 of 8 patients (75) and had progressed in 2 of 8 patients (25). Curvature was improved in 5 of 10 patients (50) and remained unchanged in 5 of 10 patients (50) of the study group; while no improvement could be recorded in any of the patients of the control group. Three of five patients (60) of

C3-C 4 intermediate photosynthetic characteristics of cassava (Manihot esculenta Crantz) : I. Gas exchange.

The gas exchange characteristics of cassava were compared with one C3 species, common bean, and two C4 species, maize and amaranthus. Cassava leaf photorespiration, about 12% of maximum net photosynthesis in normal air, and the CO2 release in CO2-free air under intense light were lower than the values typically reported for C3 species. The CO2 compensation point of whole leaves (25 cm(3) CO2m(-3)) was intermediate between C3 and C4 species values.Gas exchange was restricted to either the upper or lower surface of amphistomatous leaves by covering one side of the leaf with silicone grease. The CO2 compensation point of the upper leaf surface was less than 6 cm(3) CO2m(-3) and the CO2 release into CO2-free air in the light was essentially zero. On the lower leaf surface considerable CO2 release occurred in both the light and the dark.The hypothesis presented to explain these results is the existence of an efficient CO2 recycling mechanism in the palisade layer in the upper half of the leaf. In the light of recent data (presented in the second paper of this series) indicating that cassava produces C4 acids as primary products of photosynthesis, it is proposed that this hypothesis is consistent with the possible existence of the C4 photosynthetic pathway in the palisade layer of cassava leaves.The results and hypothesis are discussed in relation to the crop's adaptation to the environmental conditions where it is normally grown. The implications of variation in anatomical features such as stomatal distribution on both surfaces of the leaf are analyzed with a view to enhancing the potential productivity of cassava under stress conditions.

C3-C 4 intermediate photosynthetic characteristics of cassava (Manihot esculenta Crantz) : II. Initial products of(14)CO 2 fixation.

Cassava, bean and maize leaves were fed with(14)CO2 in light and the primary products of photosynthesis identified 5 and 10 seconds after assimilation. In maize, approximately three quarters of the labelled carbon was incorporated in C4 acids, in beans about two thirds in PGA, and in cassava approximately 40-60% in C4 acids with 30-50% in PGA. These data indicate that cassava possesses the C4 photosynthetic cycle, however due to the lack of typical Kranz anatomy appreciable carbon assimilation takes place directly through the Calvin-Benson-Bassham cycle.

Differential response of stomata to air humidity in the parasitic mistletoe (Phthirusa pyrifolia) and its host, mandarin orange (Citrus resitulata).

Measurements of CO2 and H2O exchange rate and the calculated leaf conductance of attached leaves were conducted over a range of leaf-to-air vapour pressure difference (VPD) (1.5 to 5.5 kPa) to compare the response of the parasitic mistletoe, Phthirusa pyrifolia, with that of its host, the mandarin orange, Citrus reticulata. Seedlings of the host infected with the parasite were grown in well-watered and adequately fertilized large pots outdoors at the CIAT headquarters, Palmira, Colombia, South America. Observations of leaf anatomy of the parasite and nutrient analysis of young tissues of both the parasite and host were made. The photosynthetic rate of the host decreased linearly with increased VPD, whereas the parasite showed a constant rate. This trend coincided with similar responses in leaf conductance. Due to the insensitivity of the parasite stomata, the transpiration rate increased linearly with VPD as compared with an initial increase and then a decrease in the host transpiration rate. The higher photosynthetic rate and the closure of stomata of the host resulted in high water use efficiency as compared with that of the parasite. The parasite accumulated in its leaves more N, P, K and less Ca and Mg than the host. The significance of the host-parasite differential response to air humidity is discussed in relation to mechanism underlying stomatal sensitivity and in the context of host-parasite association.

Stomatal response to air humidity and its relation to stomatal density in a wide range of warm climate species.

The gas exchange of 19 widely different warm climate species was observed at different leaf to air vapour pressure deficits (VPD). In all species stomata tended to close as VPD increased resulting in a decrease in net photosynthesis. The absolute reduction in leaf conductance per unit increase in VPD was greatest in those species which had a large leaf conductance at low VPDs. This would be expected even if stomata of all species were equally sensitive. However the percentage reduction in net photosynthesis (used as a measure of the relative sensitivity of stomata of the different species) was also closely related to the maximal conductance at low VPD. Similarily the relative sensitivity of stomata to changes in VPD was closely related to the weighted stomatal density or 'crowding index'.The hypothesis is presented that stomatal closure at different VPDs is related to peristomatal evaporation coupled with a high resistance between the epidermis and the mesophyll and low resistance between the stomatal apparatus and the epidermal cells. This hypothesis is consistent with the greater relative sensitivity of stomata on leaves with a high crowding index.The results and the hypothesis are discussed in the light of selection, for optimal productivity under differing conditions of relative humidity and soil water availablility, by observation of stomatal density and distribution on the two sides of the leaf.

Influence of differences in leaf anatomy on net photosynthetic rates of some cultivars of Cassava.

Gas exchange measurements and leaf anatomy of 10 cassava cultivars were conducted to study the interrelationship between the relatively high photosynthetic rates and the factors limiting internal CO2 diffusion. The internal mesophyll surface area per unit leaf surface area (A(mes)/A) and the intracellular components of CO2 diffusion and fixation resistance (R(cell)CO2) were determined. Among the group of cultivars tested net CO2 exchange rates were 26±2.5 µmol CO2 m(-2) s(-1) in normal air and intense light and A(mes)/A ranged from 14 to 38. Estimated R(cell)CO2 ranged from 4300 to 13,000 s m(-1). The combined and compensating effects of A(mes)/A and R(cell)CO2 accounted for both the high net photosynthetic rates (Pn) and the lack of large differences in Pn among cultivars.

Photosynthetic responses of cassava cultivars (Manihot esculenta Crantz) from different habitats to temperature.

Maximum photosynthetic CO2 exchange rates (Pn) of single attached leaves were determined for several cassava cultivars selected from different habitats and grown in pots outdoors at CIAT, Colombia, S.A. Pn rates were in a narrow range of 22 to 26 µmol CO2 m(-2)s(-1) for all cultivars tested when measured at high photon flux density, normal air, optimum temperature and with low leaf-air vapor pressure differences. For all tested cultivars (9 cvs.), there was a broad optimum temperature for Pn between 25 to 35°C. At temperatures below and above this range Pn declined in all cultivars with Pn rates reaching 80% of maximum at 20 and 40°C. Pn temperature coefficient (Q10) from 15-25°C was 1.6±0.2 across cultivars. No consistent relation existed between Pn, optimum temperature, and the original habitat.