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The development of the nervous system of amphioxus was investigated at the cellular level based on the expression of the pan-neuronal marker gene Hu/elav. In situ hybridization analysis showed that an amphioxus Hu/elav homolog (AmphiHu/Hel) was expressed in individual cells within the neural plate, but the cells exhibited no obvious arrangements in early embryos without distinct somites. However, in neurulae with somites, AmphiHu/Hel-positive cells were clustered along the D-V axis in close register with the boundaries of somites, resulting in reiterated cell arrangements that became evident along the neuraxis. Furthermore, AmphiHu/Hel-positive cell clusters appeared one by one along with the development of underlying somites. Double-staining in situ hybridization analysis with the islet gene revealed that the cell clusters contain presumptive motoneurons. In addition, AmphiHu/Hel expression was also observed outside the CNS, probably in the epithelial ectoderm, suggesting that amphioxus has a large number of putative sensory cell precursors as early as the early neurula stage. Taking recent gene expression studies and anatomical studies into consideration, we discuss ontogenetic and phylogenetic features of the amphioxus nervous system.

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The notochord is one of the diagnostic features of the phylum Chordata. Despite the similarities in the early morphogenetic patterns of the notochords of various chordates, they are strikingly distinct from one another at the histological level. The amphioxus notochord is one example of an evolutionary novelty because it is made up of muscle cells. Our previous expressed sequence tag analysis, targeting messenger RNAs expressed in the adult amphioxus notochord, demonstrated that many muscle-related genes are expressed there. To characterize amphioxus notochord cells and to gain insights into the myogenic program in the notochord, we determined the spatial and temporal expre-ssion patterns of these muscle-related genes during amphioxus development. We found that BbNA1 (notochord actin), Amphi-Trop I (troponin I), Amphi-TPmyosin (tropo-myosin), Amphi-MHC2 (myosin heavy chain), Amphi-nMRLC (notochord-specific myosin regulatory light chain), Amphi-nTitin/MLCK (notochord-specific titin/myosin light chain kinase), Amphi-MLP/CRP3 (muscle LIM protein), and Amphi-nCalponin (notochord-specific calponin) are expres-sed with characteristic patterns in notochord cells, including the central cells, dorsally located cells, and ventrally located cells, suggesting that each notochord cell has a unique molecular architecture that may reflect its function. In addition, we characterized two MyoD genes (Amphi-MyoD1 and Amphi-MyoD2) to gain insight into the genetic circuitry governing the formation of the notochord muscle. One of the MyoD genes (Amphi-MyoD2) is expressed in the central notochord cells, and the coexistence of Amphi-MyoD2 transcripts along with the Amphi-MLP/CRP3 transcripts implies the participation of Amphi-MyoD2 in the myogenic program in the notochord muscle.

14The ongoing development of new advanced technologies, created increasing demands for 15 rare earth elements (REEs) in the international market. The available conventional 16 technologies for concentration and recovery of REEs are expensive making biosorption an 17 efficient and low-cost technology for the recovery of REEs from aqueous solution. Thus, 18 the biosorption and desorption of multi-component solution containing Y(III), La(III), 19Sm(III), Dy(III), Pr(III), Nd(III), Gd(III) were investigated using dried or 250˚C and 350˚C 20 carbonized parachlorella. Evaluating the effect of pH with respect to contact time indicated 21 2 a dependency of the system with those parameters. The optimum pH for dried and 250˚C 22 carbonized parachlorella was 7 whereas 350˚C reaches it maximum uptake at pH 4. Rapid 23 adsorption within the first 5 min of contact followed by a slight variation the following 20 24 min characterized the sorption processes onto parachlorella by-products. The mechanism of 25 the biosorption is explained by a combination of complex reactions occurring 26 simultaneously in the biosorption process. 27 In addition, desorption process has been investigated using various concentrations of HCl, 28 HNO 3 , and H 2 SO 4 at different temperatures. It was found that the reversible process is rapid, 29 less temperature and pH dependent with high desorption percentage. Moreover, only light 30 REEs were desorbed regardless of the kind of acid and the solution temperature. 31Parachlorella is found to be good and low-cost biosorbent for the recovery of above REEs 32 from aqueous solutions. 33 34 35 36Rare earth elements (REEs) are often referred as the "seeds of technology" because 38 of their uses in high-tech strength permanent magnets, lasers, automotive catalytic 39 converters, fiber optics/superconductors, electronic devices, and green energy sectors [1, 2]. 40Due to the ongoing development of new advanced technologies, there is an over-increasing 41 demand for REEs in the international markets, with emphasis on identifying new resources 42 to ensure adequate supply for present and future use. 43 3The designation "rare earths" refers to the 15 elements of the periodic table known 44 as "lanthanides" with yttrium and scandium, further divided as a function of their atomic 45 number into two categories. Light rare earth elements (LREE), which accounted for 66.8% 46 of global demand in 2010 [2] referred to lanthanum, cerium, praseodymium, neodymium, 47 promethium and samarium. Heavy rare earths elements (HREE), less common and more 48 valuable, referred to the rest of lanthanides elements with yttrium. The 17 REEs are found 49 in all REE geological deposits because they share many similar properties but their 50 distribution and concentrations vary [2]. REE mineral deposits are usually rich in either 51 LREE or HREE, but rarely contain both in significant quantities [2]. The term "rare earth" 52 is actually a misnomer, because these elements are more abundant in the earth's crust 53 compared to silver, gold...