Preferential feeding behaviour of Daphnia magna

Preferential feeding behaviour by Daphnia magna was shown when Daphnia were fed on a mixture of ¹⁴C-labelled algae (Chlorella vulgaris or Scenedesmus quadricauda) and ³H-labelled bacteria (Escherichia coli). Daphnia consumption of bacteria was equal or higher in the presence of algae. On the other hand, in the presence of bacteria, algal consumption decreased by 40–70% compared to algal consumption in the absence of bacteria. ¹⁴C radioactive uptake was in good agreement with the chlorophyll content and demonstrates the preferential feeding behaviour of Daphnia.     

Expressed variants of Δ12-fatty acid desaturase for the high oleate trait in spanish market-type peanut lines

Increasing the oleic to linoleic acid ratio (O/L) in peanut has positiveeffects on peanut quality and its nutritional value. ¹²-Fattyacid desaturases (¹²-Fad) have been targeted as logicalcandidates controlling the high oleate trait. A previous study using genomicDNA identified an insertion and a polymorphism resulting in an amino acid changeassociated with the high oleate trait in Spanish-type peanut cultivars. Theobjectives of this research were to use RT-PCR to confirm that the SingleNucleotide Polymorphims (SNPs) identified by analysis of genomic DNA wereexpressed, and to determine if expression patterns for ¹²-Fadwere the same in both seeds and leaves. A polymorphic region of the¹²-Fad containing a series of nucleotide changes wasamplified, cloned, and sequenced from mRNA of 155 clones of two parental linesand their independent derived backcross lines (IDBLs). The latter differed intheir oleic to linoleic ratio. Data indicated that the Ainsertion and the amino acid change were expressed in both leaf and seed tissue of thehigh and low-intermediate O/L genotypes. It is postulated that several copiesof the ¹²-Fad are present in the genome. It is reasonable toconclude that total activity, and ultimately the O/L ratio, is dependent on thenumber of functional copies. The results provide the basis for an assay toscreen for the high O/L ratio at the molecular level. We also report thepresence of another isozyme of ¹²-Fad with high homology tosoybean isozyme 2 that was expressed in seeds. These authors contributed equally to this work     

Yeast communities associated with stingless bees

The yeast communities associated with the stingless bees Tetragonisca angustula, Melipona quadrifasciata and Frieseomelitta varia were studied. The bees T. angustula and F. varia showed a strong association with the yeast Starmerella meliponinorum. M. quadrifasciata more frequently carried a species related to Candida apicola, but also vectored low numbers of S. meliponinorum. Some of the yeasts isolated from adult bees were typical of species known to occur in flowers. Other yeast species found in adult bees were more typical of those found in the phylloplane. S. meliponinorum and the species in the C. apicola complex, also part of the Starmerella clade, may have a mutualistic relationship with the bees studied. Many yeasts in that group are often found in bees or substrates visited by bees, suggesting that a mutually beneficial interaction exists between them.     

Improving breeding efficiency in potato using molecular and quantitative genetics

Key message

Potatoes are highly heterozygous and the conventional breeding of superior germplasm is challenging, but use of a combination of MAS and EBVs can accelerate genetic gain.

Abstract

Cultivated potatoes are highly heterozygous due to their outbreeding nature, and suffer acute inbreeding depression. Modern potato cultivars also exhibit tetrasomic inheritance. Due to this genetic heterogeneity, the large number of target traits and the specific requirements of commercial cultivars, potato breeding is challenging. A conventional breeding strategy applies phenotypic recurrent selection over a number of generations, a process which can take over 10 years. Recently, major advances in genetics and molecular biology have provided breeders with molecular tools to accelerate gains for some traits. Marker-assisted selection (MAS) can be effectively used for the identification of major genes and quantitative trait loci that exhibit large effects. There are also a number of complex traits of interest, such as yield, that are influenced by a large number of genes of individual small effect where MAS will be difficult to deploy. Progeny testing and the use of pedigree in the analysis can provide effective identification of the superior genetic factors that underpin these complex traits. Recently, it has been shown that estimated breeding values (EBVs) can be developed for complex potato traits. Using a combination of MAS and EBVs for simple and complex traits can lead to a significant reduction in the length of the breeding cycle for the identification of superior germplasm.     

LTR retrotransposons in the <Emphasis Type="Italic">Aspergillus fumigatus</Emphasis> and <Emphasis Type="Italic">A. nidulans</Emphasis> genomes

Fungi of the genus Aspergillus can infect all tissues and organs, causing invasive mycosis (aspergillosis). This disease can be fatal, especially in immunocompromised patients. Microbiological monitoring of these infectious agents is obligatory in modern medical facilities. Mobile elements can be used as markers to identify the Aspergillus species and strains found indoors as well as to diagnose aspergillosis. Genomic sequences of two Aspergillus species, A. fumigatus and A. nidulans, were analyzed in silico in order to detect LTR retrotransposons. These species were found to considerably differ in the composition of retrotransposon families. One of the families, present in both Aspergillus species, was phylogenetically quite different from all known fungal retrotransposons. The majority of its elements were damaged copies. Nevertheless, allegedly undamaged LTR retrotransposon copies were described that contained intact ORFs and might be active.     

Isolation and characterization of sex chromosome rearrangements generating male muscle dystrophy and female abnormal oogenesis in the silkworm, Bombyx mori

In deletion-mapping of W-specific RAPD (W-RAPD) markers and putative female determinant gene (Fem), we used X-ray irradiation to break the translocation-carrying W chromosome (W ^Ze ). We succeeded in obtaining a fragment of the W ^Ze chromosome designated as Ze ^W, having 3 of 12 W-RAPD markers (W-Bonsai, W-Yukemuri-S, W-Yukemuri-L). Inheritance of the Ze ^W fragment by males indicates that it does not include the Fem gene. On the basis of these results, we determined the relative positions of W-Yukemuri-S and W-Yukemuri-L, and we narrowed down the region where Fem gene is located. In addition to the Ze ^W fragment, the Z chromosome was also broken into a large fragment (Z₁) having the + ^sch (1-21.5) and a small fragment (Z₂) having the + ^od (1-49.6). Moreover, a new chromosomal fragment (Ze ^WZ₂) was generated by a fusion event between the Ze ^W and the Z₂ fragments. We analyzed the genetic behavior of the Z₁ fragment and the Ze ^WZ₂ fragment during male (Z/Z₁ Ze ^WZ₂) and female (Z₁ Ze ^WZ₂/W) meiosis using phenotypic markers. It was observed that the Z₁ fragment and the Z or the W chromosomes separate without fail. On the other hand, non-disjunction between the Ze ^WZ₂ fragment and the Z chromosome and also between the Ze ^WZ₂ fragment and the W chromosome occurred. Furthermore, the females (2A: Z/Ze ^WZ₂/W) and males (2A: Z/Z₁) resulting from non-disjunction between the Ze ^WZ₂ fragment and the W chromosome had phenotypic defects: namely, females exhibited abnormal oogenesis and males were flapless due to abnormal indirect flight muscle structure. These results suggest that Z₂ region of the Z chromosome contains dose-sensitive gene(s), which are involved in oogenesis and indirect flight muscle development.     

Plant growth-promoting rhizobacteria do not pose any deleterious effect on cowpea and detectable amounts of ethylene are produced

Summary The use of trap crops such as cowpea could reduce the effects of the root parasitic weed, Striga hermonthica and its subsequent constraints on the growth of cereals. Certain bacteria could augment the trap crop stimulatory effect. We studied the effect of three bacteria introduced to the rhizosphere of three cowpea varieties at planting. Number of days to cowpea flowering was noted and at harvest, data were collected on pod characteristics and biomass. Means of data subjected to ANOVA were compared using Tukey’s Studentized Range Test. We analysed bacterial headspace volatiles for ethylene by gas chromatography and gas chromatography–mass spectrometry. Bacterial type significantly influenced the cowpea varieties with better performance over the non-inoculated control. Average pod weight (g) with bacterial treatment was 37.97 for Enterobacter sakazakii 8MR5, 34.38 for Pseudomonas 44MS8 and 27.46 for Pseudomonas 10M3. Non-inoculated control had an average weight of 20.98 g. Bacteria promoted a significant increase in pod weight (≥30.89%), fresh biomass (≥24.22%), and improved pod number (≥20.54%) and pod wall thickness (≥7.33%) with no deleterious effect on plant health. Ethylene released by the bacteria ranged from trace concentrations in Pseudomonas sp. to 210 nmoles/10⁸ c. f. u./ml in Ent. sakazakii 8MR5.     

New metabolites of Azotobacter vinelandii exhibiting antifungal activity

New metabolites exhibiting antifungal activity were isolated from the culture liquid of Azotobacter vinelandii strain IB 4. The metabolites were characterized by IR and ¹³C-NMR spectroscopy and defined as sucrose polythiophosphates of tetraamine (α-D-2,3-diaminoglucopyranosyl-β-D-3,4-diaminofructofuranose).