17 research outputs found
An analysis of the temperature dependence of force, during steady shortening at different velocities, in (mammalian) fast muscle fibres
We examined, over a wide range of temperatures (10–35°C), the isometric tension and tension during ramp shortening at different velocities (0.2–4 L0/s) in tetanized intact fibre bundles from a rat fast (flexor hallucis brevis) muscle; fibre length (L0) was 2.2 mm and sarcomere length ~2.5 μm. During a ramp shortening, the tension change showed an initial inflection of small amplitude (P1), followed by a larger exponential decline towards an approximate steady level; the tension continued to decline slowly afterwards and the approximate steady tension at a given velocity was estimated as the tension (P2) at the point of intersection between two linear slopes, as previously described (Roots et al. 2007). At a given temperature, the tension P2 declined to a lower level and at a faster rate (from an exponential curve fit) as the shortening velocity was increased; the temperature sensitivity of the rate of tension decline during ramp shortening at different velocities was low (Q10 0.9–1.5). The isometric tension and the P2 tension at a given shortening velocity increased with warming so that the relation between tension and (reciprocal) temperature was sigmoidal in both. In isometric muscle, the temperature T0.5 for half-maximal tension was ~10°C, activation enthalpy change (∆H) was ~100 kJ mol−1 and entropy change (∆S) ~350 J mol−1 K−1. In shortening, these were increased with increase of velocity so that at a shortening velocity (~4 L0/s) producing maximal power at 35°C, T0.5 was ~28°C, ∆H was ~200 kJ mol−1 and ∆S ~ 700 J mol−1 K−1; the same trends were seen in the tension data from isotonic release experiments on intact muscle and in ramp shortening experiments on maximally Ca-activated skinned fibres. In general, our findings show that the sigmoidal relation between force and temperature can be extended from isometric to shortening muscle; the implications of the findings are discussed in relation to the crossbridge cycle. The data indicate that the endothermic, entropy driven process that underlies crossbridge force generation in isometric muscle (Zhao and Kawai 1994; Davis, 1998) is even more pronounced in shortening muscle, i.e. when doing external work
Phoenix dactylifera (date palm; Arecaceae) putative lectin homologs: Genome-wide search, architecture analysis, and evolutionary relationship
The date palm, Phoenix dactylifera, is a vital crop in nations in the Middle East and North Africa. The date palm was thought to have outstanding traditional medicinal value because it was abundant in phytochemicals with diverse chemical structures. The date palm's ability to withstand harsh environments could be partly attributed to a class of proteins known as lectins, which are carbohydrate-binding proteins that can bind sugar moieties reversibly and without changing their chemical structures. After scanning the genome of P. dactylifera (GCF 009389715.1), this in silico study discovered 196 possible lectin homologs from 11 different families, some specific to plants. At the same time, others could also be found in other kingdoms of life. Their domain architectures and functional amino acid residues were investigated, and they yielded a 40% true-lectin with known conserved carbohydrate-binding residues. Further, their probable subcellular localization, physiochemical and phylogenetic analyses were also performed. Scanning all putative lectin homologs against the anticancer peptide (ACP) dataset found in the AntiCP2.0 webpage identified 26 genes with protein kinase receptors (Lec-KRs) belonging to 5 lectin families, which are reported to have at least one ACP motif. Our study offers the first account of Phoenix-lectins and their organization that can be used for further structural and functional analysis and investigating their potential as anticancer proteins
Seasonal Variation in Biting Rates of Simulium damnosum sensu lato, Vector of Onchocerca volvulus, in Two Sudanese Foci.
BACKGROUND:The abundance of onchocerciasis vectors affects the epidemiology of disease in Sudan, therefore, studies of vector dynamics are crucial for onchocerciasis control/elimination programs. This study aims to compare the relative abundance, monthly biting-rates (MBR) and hourly-based distribution of onchocerciasis vectors in Abu-Hamed and Galabat foci. These seasonally-based factors can be used to structure vector control efforts to reduce fly-biting rates as a component of onchocerciasis elimination programs. METHODS:A cross-sectional study was conducted in four endemic villages in Abu-Hamed and Galabat foci during two non-consecutive years (2007-2008 and 2009-2010). Both adults and aquatic stages of the potential onchocerciasis vector Simulium damnosum sensu lato were collected following standard procedures during wet and dry seasons. Adult flies were collected using human landing capture for 5 days/month. The data was recorded on handheld data collection sheets to calculate the relative abundance, MBR, and hourly-based distribution associated with climatic factors. The data analysis was carried out using ANOVA and Spearman rank correlation tests. RESULTS:Data on vector surveillance revealed higher relative abundance of S. damnosum s.l. in Abu- Hamed (39,934 flies) than Galabat (8,202 flies). In Abu-Hamed, vector populations increased in January-April then declined in June-July until they disappeared in August-October. Highest black fly density and MBR were found in March 2007 (N = 9,444, MBR = 58,552.8 bites/person/month), and March 2010 (N = 2,603, MBR = 16,138.6 bites/person/month) while none of flies were collected in August-October (MBR = 0 bites/person/month). In Galabat, vectors increased in September-December, then decreased in February-June. The highest vector density and MBR were recorded in September 2007 (N = 1,138, MBR = 6,828 bites/person/month) and September 2010 (N = 1,163, MBR = 6,978 bites/person/month), whereas, none appeared in collection from April to June. There was a significant difference in mean monthly density of S. damnosum s.l. across the two foci in 2007-2008 (df = 3, F = 3.91, P = 0.011). Minimum temperature showed significant correlation with adult flies counts in four areas sampled; the adult counts were increased in Nady village (rs = 0.799) and were decreased in Kalasecal (rs = -0.676), Gumaiza (rs = -0.585), and Hilat Khateir (rs = -0.496). Maximum temperature showed positive correlation with black fly counts only in Galabat focus. Precipitation was significantly correlated with adult flies counts in Nady village, Abu-Hamed, but no significance was found in the rest of the sampled villages in both foci. Hourly-based distribution of black flies showed a unimodal pattern in Abu-Hamed with one peak (10:00-18:00), while a bimodal pattern with two peaks (07:00-10:00) and (14:00-18:00) was exhibited in Galabat. CONCLUSION:Transmission of onchocerciasis in both foci showed marked differences in seasonality, which may be attributed to ecology, microclimate and proximity of breeding sites to collection sites. The seasonal shifts between the two foci might be related to variations in climate zones. This information on black fly vector seasonality, ecology, distribution and biting activity has obvious implications in monitoring transmission levels to guide the national and regional onchocerciasis elimination programs in Sudan
Monthly density of black flies collected in Abu-Hamed and Galabat in 2007–2008 and 2009–2010.
<p>Monthly density of black flies collected in Abu-Hamed and Galabat in 2007–2008 and 2009–2010.</p
Monthly biting-rate of the host-seeking females collected in Abu-Hamed and Galabat in 2007–2008 and 2009–2010.
<p>Monthly biting-rate of the host-seeking females collected in Abu-Hamed and Galabat in 2007–2008 and 2009–2010.</p
Temperature profile during 2007–2008 and 2009–2010 according to black fly collection activities in Abu-Hamed and Galabat, Sudan.
<p>Temperature profile during 2007–2008 and 2009–2010 according to black fly collection activities in Abu-Hamed and Galabat, Sudan.</p
Seasonal Variation in Biting Rates of <i>Simulium damnosum sensu lato</i>, Vector of <i>Onchocerca volvulus</i>, in Two Sudanese Foci
<div><p>Background</p><p>The abundance of onchocerciasis vectors affects the epidemiology of disease in Sudan, therefore, studies of vector dynamics are crucial for onchocerciasis control/elimination programs. This study aims to compare the relative abundance, monthly biting-rates (MBR) and hourly-based distribution of onchocerciasis vectors in Abu-Hamed and Galabat foci. These seasonally-based factors can be used to structure vector control efforts to reduce fly-biting rates as a component of onchocerciasis elimination programs.</p><p>Methods</p><p>A cross-sectional study was conducted in four endemic villages in Abu-Hamed and Galabat foci during two non-consecutive years (2007–2008 and 2009–2010). Both adults and aquatic stages of the potential onchocerciasis vector <i>Simulium damnosum sensu lato</i> were collected following standard procedures during wet and dry seasons. Adult flies were collected using human landing capture for 5 days/month. The data was recorded on handheld data collection sheets to calculate the relative abundance, MBR, and hourly-based distribution associated with climatic factors. The data analysis was carried out using ANOVA and Spearman rank correlation tests.</p><p>Results</p><p>Data on vector surveillance revealed higher relative abundance of <i>S</i>. <i>damnosum s</i>.<i>l</i>. in Abu- Hamed (39,934 flies) than Galabat (8,202 flies). In Abu-Hamed, vector populations increased in January-April then declined in June-July until they disappeared in August-October. Highest black fly density and MBR were found in March 2007 (<i>N</i> = 9,444, MBR = 58,552.8 bites/person/month), and March 2010 (<i>N</i> = 2,603, MBR = 16,138.6 bites/person/month) while none of flies were collected in August-October (MBR = 0 bites/person/month). In Galabat, vectors increased in September-December, then decreased in February-June. The highest vector density and MBR were recorded in September 2007 (<i>N</i> = 1,138, MBR = 6,828 bites/person/month) and September 2010 (<i>N</i> = 1,163, MBR = 6,978 bites/person/month), whereas, none appeared in collection from April to June. There was a significant difference in mean monthly density of <i>S</i>. <i>damnosum s</i>.<i>l</i>. across the two foci in 2007–2008 (df = 3, F = 3.91, <i>P</i> = 0.011). Minimum temperature showed significant correlation with adult flies counts in four areas sampled; the adult counts were increased in Nady village (<i>r</i><sub><i>s</i></sub> = 0.799) and were decreased in Kalasecal (<i>r</i><sub><i>s</i></sub> = - 0.676), Gumaiza (<i>r</i><sub><i>s</i></sub> = - 0.585), and Hilat Khateir (<i>r</i><sub><i>s</i></sub> = - 0.496). Maximum temperature showed positive correlation with black fly counts only in Galabat focus. Precipitation was significantly correlated with adult flies counts in Nady village, Abu-Hamed, but no significance was found in the rest of the sampled villages in both foci. Hourly-based distribution of black flies showed a unimodal pattern in Abu-Hamed with one peak (10:00–18:00), while a bimodal pattern with two peaks (07:00–10:00) and (14:00–18:00) was exhibited in Galabat.</p><p>Conclusion</p><p>Transmission of onchocerciasis in both foci showed marked differences in seasonality, which may be attributed to ecology, microclimate and proximity of breeding sites to collection sites. The seasonal shifts between the two foci might be related to variations in climate zones. This information on black fly vector seasonality, ecology, distribution and biting activity has obvious implications in monitoring transmission levels to guide the national and regional onchocerciasis elimination programs in Sudan.</p></div
Regional and local map of the study sites in Sudan.
<p>The areas highlighted with grey represent the two endemic foci in Abu-Hamed and Galabat. The dotted circles on the right represent the villages selected in each focus.</p
The number of adult <i>Simulium damnosum s</i>. <i>l</i>. black flies collected from Abu-Hamed and Galabat foci during 2007–2008 and 2009–2010.
<p>The number of adult <i>Simulium damnosum s</i>. <i>l</i>. black flies collected from Abu-Hamed and Galabat foci during 2007–2008 and 2009–2010.</p
Hourly-based distribution of host-seeking females sampled from human-baits collection in Abu-Hamed and Galabat, Sudan.
<p>Hourly-based distribution of host-seeking females sampled from human-baits collection in Abu-Hamed and Galabat, Sudan.</p