Asexual Reproduction

Rhizostoma pulmo is one of the most abundant scyphomedusae along the Mediterranean coasts. To understand changes in the population densities of the medusa stage and its relationship with the benthic stage, we describe all developmental stages from the life cycle of R. pulmo, from the scyphistoma stage to young medusae reared in the laboratory. Mature scyphistomae showed a mean total body length of 1.7 mm and the average tentacle number was 16. Asexual reproduction occurred by lateral budding, podocyst and pedalocyst production. Each strobila released up to 8 ephyrae that had a mean total body diameter of 3.5 mm. Moreover, we also present data on the temporal and spatial distribution of the species in the Catalan Sea and the coastal lagoon on Mar Menor (NW Mediterranean) during the years 2007–2009. In the Catalan Sea, the presence of adult R. pulmo was recorded as extended along the whole coast, but most of the observation was concentrated in the central area; the highest abundances were recorded during the months of July and August. The highest number of observations was detected in 2008 in coincidence with the inter-annual variation observed in the Mar Menor lagoon.

This study isolated a novel erythritol-producing yeast strain, which is capable of growth at high osmolarity. Characteristics of the strain include asexual reproduction by multilateral budding, absence of extracellular starch-like compounds, and a negative Diazonium blue B color reaction. Phylogenetic analysis based on the 26S rDNA sequence and physiological analysis indicated that the strain belongs to the species Pseudozyma tsukubaensis and has been named P. tsukubaensis KN75. When P. tsukubaensis KN75 was cultured aerobically in a fed-batch culture with glucose as a carbon source, it produced 245 g/L of erythritol, corresponding to 2.86 g/L/h productivity and 61% yield, the highest erythritol yield ever reported by an erythritol-producing microorganism. Erythritol production was scaled up from a laboratory scale (7 L fermenter) to pilot (300 L) and plant (50,000 L) scales using the dissolved oxygen as a scale-up parameter. Erythritol production at the pilot and plant scales was similar to that at the laboratory scale, indicating that the production of erythritol by P. tsukubaensis KN75 holds commercial potential.

Spribille, T., Schultz, M., breuSS, O. & bergmeier,�E. 2006. Notes on the lichens and lichenicolous fungi of western Crete (Greece). - Herzogia 19: 125-148. We report a total of 248 species of lichens and lichenicolous fungi from recent floristic work in western Crete. A total of 103 taxa are reported from the island for the first time; at least 16 taxa are new to Greece. Two species, Peccania teretiuscula and Verrucaria werneri, are new to Europe and both are reported for only the second time since their de- scription. Lichens that disperse by asexual reproductive structures (soredia, isidia) constitute only a small proportion of the flora and most species with this dispersal strategy are relatively infrequent. Some possible reasons for this as well as general patterns in the epiphytic lichen flora are discussed. Zusammenfassung: Spribille, T., Schultz, M., breuSS, O. & bergmeier,� E. 2006. Beitrag zur Kenntnis der Flechten und lichenicolen Pilze West-Kretas (Griechenland). - Herzo...

Seagrasses, a unique group of submerged flowering plants, profoundly influence the physical, chemical and biological environments of coastal waters through their high primary productivity and nutrient recycling ability. They provide habitat for aquatic life, alter water flow, stabilize the ground and mitigate the impact of nutrient pollution. at the coast region. Although on a global scale seagrasses represent less than 0.1% of the angiosperm taxa, the taxonomical ambiguity in delineating seagrass species is high. Thus, the taxonomy of several genera is unsolved. While seagrasses are capable of performing both, sexual and asexual reproduction, vegetative reproduction is common and sexual progenies are always short lived and epimeral in nature. This makes species differentiation often difficult, especially for non-taxonomists since the flower as a distinct morphological trait is missing. Our goal is to develop a DNA barcoding system assisting also non-taxonomists to identify regional...

• Understanding apomixis (asexual reproduction through seeds) is of great interest to both plant breeders and evolutionary biologists. The genus Boechera is an excellent system for studying apomixis because of its close relationship to Arabidopsis, the occurrence of apomixis at the diploid level, and its potentially simple inheritance by transmission of a heterochromatic (Het) chromosome.• Diploid sexual Boechera stricta and diploid apomictic Boechera divaricarpa (carrying a Het chromosome) were crossed. Flow cytometry, karyotype analysis, genomic in situ hybridization, pollen staining and seed-production measurements were used to analyse the parents and resulting F1, F2 and selected F3 and test-cross (TC) generations.• The F1 plant was a low-fertility triploid that produced a swarm of aneuploid and polyploid F2 progeny. Two of the F2 plants were fertile near-tetraploids, and analysis of their F3 and TC progeny revealed that they were sexual and genomically stabilized.• The apomictic phenotype was not transmitted by genetic crossing as a single dominant locus on the Het chromosome, suggesting a complex genetic control of apomixis that has implications for future genetic and evolutionary analyses in this group.Understanding apomixis (asexual reproduction through seeds) is of great interest to both plant breeders and evolutionary biologists. The genus Boechera is an excellent system for studying apomixis because of its close relationship to Arabidopsis, the occurrence of apomixis at the diploid level, and its potentially simple inheritance by transmission of a heterochromatic (Het) chromosome.Diploid sexual Boechera stricta and diploid apomictic Boechera divaricarpa (carrying a Het chromosome) were crossed. Flow cytometry, karyotype analysis, genomic in situ hybridization, pollen staining and seed-production measurements were used to analyse the parents and resulting F1, F2 and selected F3 and test-cross (TC) generations.The F1 plant was a low-fertility triploid that produced a swarm of aneuploid and polyploid F2 progeny. Two of the F2 plants were fertile near-tetraploids, and analysis of their F3 and TC progeny revealed that they were sexual and genomically stabilized.The apomictic phenotype was not transmitted by genetic crossing as a single dominant locus on the Het chromosome, suggesting a complex genetic control of apomixis that has implications for future genetic and evolutionary analyses in this group.

Michetti, K. M.; P. I. Leonardi & E. J. Cáceres. 2007. Vegetative morphology and asexual reproduction of Draparnaldia mutabilis (Chaetophoraceae, Chlorophyta), first verified record for Argentina. Darwiniana 45(2): 175-180. Thalli of Draparnaldia mutabilis consist of a reduced, prostrate rhizoidal system and an erect system with marked differentiation between axial and lateral, highly branched, filaments, grouped in dense fascicles. The asexual

Sex in eukaryotes involves a combination of meiosis and syngamy; absence of these processes leads to asexual reproduction of which there are different kinds (Box 9.1). Lineages comprising subsequent generations of such asexually reproducing individuals are nearly invariably referred to as clones. In addition, they are mostly identified by genetic techniques using different molecular markers and with differing powers of resolution. Here, we demonstrate that various clonal concepts are being used without clear discrimination, which can significantly impede both the repeatability of, and comparisons between, studies. An example of the resulting dilemma is that, according to one concept, the more than 350 species of obligate asexual bdelloid rotifers all belong to one clone, whereas according to another concept, each of these species comprises several clones.