Stability via asynchrony in Drosophila metapopulations with low migration rates

Very few experimental studies have examined how migration rate affects metapopulation dynamics and stability. We studied the dynamics of replicate laboratory metapopulations of Drosophila under different migration rates. Low migration stabilized metapopulation dynamics, while promoting unstable subpopulation dynamics, by inducing asynchrony among neighboring subpopulations. High migration synchronized subpopulation dynamics, thereby destabilizing the metapopulations. Contrary to some theoretical predictions, increased migration did not affect average population size. Simulations based on a simple non-species-specific population growth model captured most features of the data, which suggests that our results are generalizable.     

Molecular breeding for resistance to black rot [<Emphasis Type="Italic">Xanthomonas campestris</Emphasis> pv. <Emphasis Type="Italic">campestris</Emphasis> (Pammel) Dowson] in <Emphasis Type="Italic">Brassicas</Emphasis>: recent advances

The Brassicas are affected by several diseases, of which black rot, Xanthomonas campestris pv. campestris (Pam.) Dowson (Xcc), is one of the most widespread and devastating worldwide. The black rot bacteria causes systemic infection in the susceptible plants and penetrate the plants through the hydathodes or wounds. Typical disease symptoms are ‘V’ shaped necrotic lesions appearing from the leaf margins with blackened veins. Periodic outbreaks of the black rot pathogen have occurred worldwide, especially in the continental regions, where high temperatures and humidity favor the incidence of disease occurrence causing huge yield loss. The challenge to control the losses in vegetable brassicas production is made more difficult by the adverse climatic changes and evolution of new pathogenic races. The development of black rot resistant hybrids/varieties is the most reliable long term practical solution for effective disease control. Identification of new resistant genetic resources, tightly linked markers with resistance loci and QTL mapping would facilitate the breeding programme for black rot resistance. Information regarding genetics of resistance and mapping of resistance genes/QTLs will accelerate the marker assisted resistance breeding in brassica crops against Xcc. In future we need to identify the race specific candidate genes for and their validation through transgenics and gene expression. Moreover, it is imperative to identify functional markers for resistance genes through identification of R gene families and their relationship with resistance expression. This comprehensive review will help the researchers working in this area to understand the dynamics of black resistance breeding and to formulate future breeding strategies.     

Cytoplasmic male sterile and doubled haploid lines with desirable combining ability enhances the concentration of important antioxidant attributes in <Emphasis Type="Italic">Brassica oleracea</Emphasis>

The Brassica vegetable crops are rich source of important antioxidant compounds having anticancer and health promoting properties. Development of F₁ hybrids with better nutritional traits is one of the main breeding objectives in different vegetable crops. Our study is the first report of determining heterotic combinations utilizing cytoplasmic male sterile (CMS) and doubled haploid (DH) inbred lines for antioxidant compounds in snowball cauliflower. Twenty genetically diverse Ogura CMS lines of cauliflower and six DH male fertile inbred lines were crossed to develop 120 F₁ hybrids in line?×?tester mating design. The resulting 120 test cross progenies along with 26 parents and 4 standard checks were evaluated in 10?×?15 alpha lattice design with three replications during next cropping season. The CMS lines Ogu33-1A, Ogu122-5A and Ogu119-1A were good general combiner and CMS line Ogu118-6A was poor general combiner for majority of traits. Most of the heterotic hybrids were associated with high positive SCA effects. The proportions of σ²A/D and \(\upsigma^{2}_{\text{gca}} /\upsigma^{2}_{\text{sca}}\) ratios were less than unity in all the cases indicating preponderance of non-additive gene action in the genetic control of all the traits. Highest number of heterotic hybrids with SCA effects in desired positive direction was recorded for ascorbic acid content and phenolic content followed by total carotenoid content. The F₁ hybrids with better combining ability and better per se performance could be useful in accumulation of favourable allele for higher concentration of important anti-oxidant compounds.     

Elevated carbon dioxide level along with phosphorus application and cyanobacterial inoculation enhances nitrogen fixation and uptake in cowpea crop

Climate change, as a result of increase in the concentration of greenhouse gases, influences growth and productivity of leguminous crops. A study was carried out to analyse the impacts of elevated carbon dioxide (CO₂) and cyanobacterial inoculation on growth, N₂ fixation and N availability and uptake in cowpea crop, under different doses of phosphorus. Cowpea crop was grown under ambient (400 µmol mol^?1) and elevated (550 ± 20 µmol mol^?1) CO₂ levels using Free-Air Carbon dioxide Enrichment facility. Elevated CO₂ level increased chlorophyll content in leaves, improved nodulation and nitrogen fixation by the crop. Increase in P dose up to 16 mg kg^?1 soil enhanced nodule development and N₂ fixation under high CO₂ condition. Cyanobacterial inoculation increased nodule weight, leghaemoglobin content in nodules and total nitrogenase activity. Although nitrogen concentration in cowpea seeds decreased in high CO₂ treatment, higher N uptake was recorded. Under elevated CO₂ condition, cyanobacterial inoculation and higher P doses led to enhanced root growth and N₂ fixation and availability of soil nitrogen. The study illustrated the synergistic effect of high CO₂ and cyanobacterial inoculation in enhancing crop growth and availability of soil N, mediated by biological N₂ fixation in cowpea under different levels of P.     

Pharmacokinetics of clindamycin HCl administered intravenously, intramuscularly and subcutaneously to dogs

A buffered aqueous solution of clindamycin Hcl (200 mg/mL) was injected intravenously (i.v.) intramuscularly (i.m.) and subcutaneously (s.c.) in a non-randomized, partial cross-over trial involving six male and six female dogs. Blood samples were collected at conventional, predetermined time periods and serum drug concentrations were determined by microbiological assay. Dogs were observed clinically for signs of pain, and activity of serum creatine phosphokinase (CPK) was monitored after i.m. dosing. The i.v. data from five of the dogs best fitted a two-compartment open-system pharmacokinetic model whereas a non-compartment model was most suitable for analysis of the data from the remaining seven dogs. The mean i.v. elimination half-life (t1/2 beta) and the mean residence time (MRT) were 124 and 143 min, respectively. The mean volume of distribution at steady state (Vss) was 0.86 L/kg. Little pain was recorded upon i.m. injection; mean peak serum drug concentration (Cmax) was 4.4 micrograms/mL, the elimination half-life (t1/2el) was 247 min and the calculated bioavailability (F) was 115% of the i.v. dose. Serum CPK activity was elevated to 25-fold the pretreatment level in samples collected 4, 8 and 12 h after i.m. injection. Pain was not recorded after s.c. drug administration; the mean Cmax of 20.8 micrograms/mL was significantly greater than the corresponding value for the i.m. route, and F was 310%. The s.c. route appears to be superior to the i.m. route in terms of local tolerance and serum drug level; a 10 mg/kg SID treatment regimen is suggested for treatment of canine infections due to clindamycin sensitive bacteria.     

Molecular characterization and induced expression analysis of the terminal complement component C9 in rohu,Labeo rohita

The complement component 9 (C9) plays a significant role in the formation of membrane attack complex (MAC) on the targeted cell surface. The current study is dealt with molecular characterization of C9 gene from rohu, Labeo rohita, an important cultured carp species in India. An open reading frame (ORF) of 1998 bp was amplified by polymerase chain reaction (PCR) that encodes a polypeptide of 666 amino acids having a signal peptide of 19 amino acids and a mature peptide of 647 amino acids. The SMART domain architecture analysis revealed two thrombospondin type‐1 domains (TSP1), a low‐density lipoprotein receptor domain class A (LDLa), a membrane attack complex and perforin (MACPF) domain, and an epidermal growth factor (EGF)‐like domain. Multiple sequence alignment and evolutionary analysis revealed a primitive C9 sequence of rohu with maximum similarity and clustering with common carp, grass carp and zebrafish. C9 was highly expressed in liver and constitutively expressed in wide array of tissues except in eye of rohu juveniles. It was expressed during early developmental days of rohu including in milt. A variable level of up‐regulation in C9 expression was noticed upon poly I:C induction, Aeromonas hydrophila and Argulus siamensis infections in liver, spleen and gill tissues of rohu at different time points. A constitutive expression of C9 in different stages of rohu during the ontogeny and in response to pathogen exposures along with high degree of sequence homology with other fish species proved it as an important primitive immune molecule of the complement system lytic pathway.