Australian Laurencia majuscula (Rhodophyta,Rhodomelaceae) and the Brazilian Laurencia dendroidea are conspecific

Morphological and molecular studies have been undertaken on two species of the red algal genus Laurencia J.V.Lamouroux: Laurencia majuscula (Harvey) A.H.S. Lucas and Laurencia dendroidea J.Agardh, both from their type localities. The phylogenetic position of these species was inferred by analysis of the chloroplast‐encoded rbcL gene sequences from 24 taxa. In all phylogenetic analyses, the Australian Laurencia majuscula and the Brazilian L. dendroidea formed a well‐supported monophyletic clade within the Laurencia sensu stricto. This clade was divided into two subclades corresponding to each geographical region; however, the genetic divergence between Australian L. majuscula and Brazilian L. dendroidea was only 0–1.35%. Examination of the type specimens and sequences of freshly collected samples of both Laurencia majuscula and L. dendroidea show the two to be conspecific despite their disjunct type localities.     

Additional analysis of chemical diversity of the red algal genus Laurencia (Rhodomelaceae) from Japan

The halogenated secondary metabolite constitution of four species of the red algal genus Laurencia (Rhodomelaceae) from southern Japan is reported. Laurencia composita Yamada from Tanegashima Island (Kagoshima Prefecture) bears five sesquiterpenoids (2,10‐dibromo‐3‐chloro‐α‐chamigrene and 2,10‐dibromo‐3‐chloro‐9‐hydroxy‐α‐chamigrene, in addition to pre‐pacifenol epoxide, johnstonol and pacifenol, which are known in other populations of this species). Laurencia intricata Lamouroux from Chinzei (Saga Prefecture) and Oomura Bay (Nagasaki Prefecture) bear a C₁₅ aceto‐genin, okamurallene. Laurencia majuscula (Harvey) Lucas from Tanegashima Island produces three sesquiterpenoids, (Z)‐10,15‐dibromo‐9‐hydroxy‐chamigra‐1, 3(15),7(14)‐triene, 10‐bromo‐7‐hydroxylaurene and 10,11‐dibromo‐7‐hydroxylaurene, corresponding to those of one of its chemical races. Laurencia venusta Yamada from Tanegashima Island produces two sesquiterpenoids, cupalaurenol and cyclolaurenol, which were known only from a sea hare, Aplysia dactylomela Rang. This strongly suggests that Aplysia consumes L. venusta and concentrates these halogenated compounds.     

ECOPHYSIOLOGY OF TROPICAL RHODOPHYTES. II. MICROSCALE ACCLIMATION IN PHOTOSYNTHESIS1

Parameters of photosynthesis vs. irradiance curves varied markedly between tissues from microsites along the < 10-cm axes of the tropical intertidal red algae Ahnfeltiopsis concinna (J. Ag.) Silva et DeCew and Laurencia mcdermidiae (J. Ag.) Abbott. Differences in photosynthetic performance between tissues from canopy and understory microsites indicates that L. mcdermidiae exhibited an expected sun-to-shade acclimation but over the space of < 10 cm. Respiration, I_c, I_k, and P_max values were significantly lower in tissues from the understory relative to tissues from the canopy of L. mcdermidiae, while photosystem I (PS I) sizes (PSU I) were significantly higher in tissues from understory microsites. Quantum efficiency was unchanged. Ahnfeltiopsis concinna, in contrast, exhibited higher α in tissues from understory rather than canopy microsites. The values of P_max for tissues from the canopy of A. concinna were not higher than the understory, while PSU O₂(PS II size) of tissues from canopy microsites were unusually higher than those of understory microsites. These characteristics suggest a high degree of irradiance stress in tissues from the canopy of A. concinna, the highest tidal alga in Hawaiian coastal zones. Acclimation to high photosynthetically active radiation and ultraviolet irradiance levels especially in tropical regions appears to be an essential mechanism(s) for stress resistance and persistence of intertidal algae. Algal turfs acclimate at microscales in part fostered by their dense stands that create sharp irradiance gradients as well as adjust physiologically to canopy irradiance levels as mechanisms for optimal photosynthetic performance and stress tolerance.     

PHYLOGENY OF THE EUGLENALES BASED UPON COMBINED SSU AND LSU RDNA SEQUENCE COMPARISONS AND DESCRIPTION OF DISCOPLASTIS GEN. NOV. (EUGLENOPHYTA)1

A Bayesian analysis, utilizing a combined data set developed from the small subunit (SSU) and large subunit (LSU) rDNA gene sequences, was used to resolve relationships and clarify generic boundaries among 84 strains of plastid‐containing euglenophytes representing 11 genera. The analysis produced a tree with three major clades: a Phacus and Lepocinlis clade, a Discoplastis clade, and a Euglena, Colacium, Trachelomonas, Strombomonas, Monomorphina, and Cryptoglena clade. The majority of the species in the genus Euglena formed a well‐supported clade, but two species formed a separate clade near the base of the tree. A new genus, Discoplastis, was erected to accommodate these taxa, thus making the genus Euglena monophyletic. The analysis also supported the monophyly of Colacium, Trachelomonas, Strombomonas, Monomorphina, and Cryptoglena, which formed two subclades sister to the Euglena clade. Colacium, Trachelomonas, and Strombomonas, all of which produce copious amounts of mucilage to form loricas or mucilaginous stalks, formed a well‐supported lineage. Our analysis supported retaining Strombomonas and Trachelomonas as separate genera. Monomorphina and Cryptoglena formed two well‐supported clades that were sister to the Colacium, Trachelomonas, and Strombomonas clade. Phacus and Lepocinclis, both of which have numerous small discoid chloroplasts without pyrenoids and lack peristaltic euglenoid movement (metaboly), formed a well‐supported monophyletic lineage that was sister to the larger Euglena through Cryptoglena containing clade. This study demonstrated that increased taxon sampling, multiple genes, and combined data sets provided increased support for internal nodes on the euglenoid phylogenetic tree and resolved relationships among the major genera in the photosynthetic euglenoid lineage.     

Origin of the pantropical and nutriceutical Morinda citrifolia L. (Rubiaceae): comments on its distribution range and circumscription

Aim Morinda citrifolia L., commercially known as noni or the Indian mulberry plant, is morphologically variable and the only widely distributed member of the pantropical genus Morinda sensu stricto (Rubiaceae). This large distribution has been attributed partly to the ability of the seeds of the large‐fruited M. citrifolia L. var. citrifolia L. to be transported by oceanic drifting. This form of M. citrifolia var. citrifolia has been predicted to be the progenitor colonizer of the island endemic Morinda species. Using a phylogenetic approach and large sampling of the widespread, large‐fruited M. citrifolia var. citrifolia, we assessed the potential area of origin of M. citrifolia and tested the hypothesis that the large‐fruited M. citrifolia var. citrifolia is an ancestral colonizer. Location Tropics. Methods We performed Bayesian analyses of 22 species of the tribe Morindeae (including 11 individuals of the three currently recognized varieties of M. citrifolia) based on combined nrETS, nrITS, rps16 and trnT–F sequence data. Geographic origins of the studied taxa were mapped onto the Bayesian majority rule consensus tree. Results Nine sequenced individuals of M. citrifolia from diverse geographic locations formed a highly supported clade, which was sister to the Australo‐Micronesian clade that included M. bracteata var. celebica and M. latibracteata. These sister clades are part of the broader Asian, arborescent Morinda clade. We found no support for the current varietal classification of M. citrifolia. Main conclusions Our analyses suggest a Micronesian origin of M. citrifolia. This implies that the large‐fruited M. citrifolia var. citrifolia might well have been present in the Pacific before the arrival of the Micronesian and Polynesian ancestors from Southeast Asia. The wide distribution of this form of M. citrifolia var. citrifolia is attributed partly to the trans‐oceanic dispersal of its buoyant seeds, self‐pollination and its ability to produce flowers and fruits year‐round. The hypothesis that the widespread, large‐fruited M. citrifolia var. citrifolia is the progenitor colonizer of the island endemic Morinda species is inconsistent with its derived position within the Asian, arborescent Morinda clade and with the fact that the nine sampled individuals of M. citrifolia form a clade.     

Advance in research of microRNA in Caenorhabditis elegans

microRNA (miRNA) is a family of small, non‐coding RNA first discovered as an important regulator of development in Caenorhabditis elegans (C. elegans). Numerous miRNAs have been found in C. elegans, and some of them are well conserved in many organisms. Though, the biologic function of miRNAs in C. elegans was largely unknown, more and more studies support the idea that miRNA is an important molecular for C. elegans. In this review, we revisit the research progress of miRNAs in C. elegans related with development, aging, cancer, and neurodegenerative diseases and compared the function of miRNAs between C. elegans and human. J. Cell. Biochem. 114: 994–1000, 2013. © 2012 Wiley Periodicals, Inc.     

ECOPHYSIOLOGY OF TROPICAL RHODOPHYTES. I. MICROSCALE ACCLIMATION IN PIGMENTATION1,2

Microscale pigment adjustments to a tropical photosynthetically active radiation and ultraviolet (UV) environment by the intertidal turf algae Ahnfeltiopsis concinna (J. Ag.) Silva et DeCew and Laurencia mcdermidiae (J. Ag) Abbott were promoted by thalli densities that self-shade the under story portions of the same diminutive axes. Tissues of A. concinna from canopy microsites had significantly reduced levels of phycoerythrin, phycocyanin, and allophycocyanin compared to tissues from understory microsites of the same axes. Tissues of L. mcdermidiae from canopy microsites had reduced levels of only phycoerythrin compared to tissues from understory microsites. These alterations coupled with enhanced levels of carotenoid and UV-absorbing compounds in tissues from canopy compared to tissues from understory microsites indicated a pattern of remarkably sensitive photoacclimation over the ≤10-cm axes of these turf-forming rhodophytes. Microscale variation in the in vivo UV absorbance capabilities for turfs of A. concinna and L. mcdermidiae was directly related to the amount of extractable UV-absorbing compounds. An in vivo absorbance signature at ～345 nm appears to provide a method to quickly and accurately gauge the potential UV-shielding capacity of primary producers even at remarkably fine ecological scales. The capacity for highly responsive biochemical adjustments that result in marked canopy–understory distinctions coupled with a turf morphology may be crucial for macroalgal tolerance of physiological stresses associated with tropical intertidal zones. This responsive capacity allows for enhanced photoprotective mechanisms in tissues from canopy microsites while optimizing irradiance capture in deeply shaded tissues from understory microsites < 10 cm away.     

Sesquiterpenoids of Laurencia majuscula (Ceramiales, Rhodophyta) from the Ryukyu Islands, Japan

Two populations of the red alga Laurencia majuscula (Harvey) Lucas (Rhodomelaceae, Ceramiales) from Taketomi Island and Hateruma Island, the Ryukyu Islands, Japan, have been characterized on the basis of both morphological features and halogenated secondary metabolite content. These populations have smaller and more slender thalli than those of other regions. Furthermore, the populations contain two chamigrane-type Sesquiterpenoids, (2R, 3R, 5S)-5-acetoxy-2-bromo-3-chlorochamigra-7(14),9-dien-8-one and (2R, 3R)-2-bromo-3-chlorochamigra-7(14), 9-dien-8-one, and a laurane-type sesquiterpenoid, debromoisolaurinterol, as secondary metabolites which are different from those previously reported from other populations. These results are consistent with the concept of ‘chemical races’ within a single species of Laurencia.     

CHARACTERIZATION OF MARTENSIA (DELESSERIACEAE,RHODOPHYTA) BASED ON A MORPHOLOGICAL AND MOLECULAR STUDY OF THE TYPE SPECIES,M. ELEGANS,AND M. NATALENSIS SP. NOV. FROM SOUTH AFRICA1

An examination of a series of collections from the coast of Natal, South Africa, has revealed the presence of two species of Martensia C. Hering nom. cons: M. elegans C. Hering 1841, the type species, and an undescribed species, M. natalensis sp. nov. The two are similar in gross morphology, with both having the network arranged in a single band, and with reproductive thalli of M. elegans usually larger and more robust than those of M. natalensis. Molecular studies based on rbcL sequence analyses place the two in separate, strongly supported clades. The first assemblage occurs primarily in the Indo‐West Pacific Ocean, and the second is widely distributed in tropical and warm‐temperate waters. Criteria that have been used in the past for separating the two, namely, the number and shape of the blades, the presence of a single‐ versus a multiple‐banded network, and blade margins entire or toothed, were determined to be unreliable. Although the examination of additional species is required, the morphology and position of procarps and cystocarps, whether at or near the corners of the longitudinal lamellae and the cross‐connecting strands or along the lobed, membranous edges of the longitudinal lamellae or on the thallus margins, may prove to be diagnostic at the subgenus level. We recognize subg. Martensia, including the type of Martensia: M. elegans and subg. Mesotrema (J. Agardh) De Toni based on Martensia pavonia (J. Agardh) J. Agardh.     

Multiple Molecular Forms of Acetylcholinesterase in the Nematode Caenorhabditis elegans

Abstract: Extracts of the nematode Caenorhabditis elegans contain five molecular forms of acetylcholinesterase (AChE) activity that can be separated by a combination of selective solubilization, velocity sedimentation, and ion-exchange chromatography. These are called form IA (5.2s), form IB (4.9.s), form II (6.7s), form III (11.3s), and form IV (13.0s). All except form III are present in significant amounts in rapidly prepared extracts and are probably native; form III is probably derived autolytically from form IV. Most of forms IA and IB can be solubilized by repeated extractions without detergent, whereas forms II, III, and IV require detergent for effective solubilization and may therefore be membrane-bound. High salt concentrations are not required for, and do not aid in, the solubilization of these forms. For all forms, molecular weights and frictional ratios have been estimated by a combination of gel permeation chromatography and velocity sedimentations in both H₂O and D₂O. The molecular weight estimates range from 83,000 to 357,000 and only form II shows extensive asymmetry. The separated forms have been characterized with respect to substrate affinity, substrate specificity, inhibitor sensitivity, thermal inactivation, and detergent sensitivity. Judging by these properties, C. elegans is like other invertebrates in that none of its cholinesterase forms resembles either the “true” or the “pseudo” cholinesterase of vertebrates. However, internal comparison of the C. elegans forms clearly distinguishes forms IA, III, and IV as a group from forms IB and II; the former are therefore designated “class A” forms, the latter “class B” forms. Genetic evidence indicates that separate genes control class A and class B forms, and that these two classes overlap functionally. Several factors, including kinetic properties, molecular asymmetry, molecular size, and solubility, all suggest that a molecular model of the multiple cholinesterase forms observed in vertebrate electric organs probably does not apply in C. elegans. Potential functional roles and subunit structures of the multiple AChE forms within each C. elegans class are discussed.     

Optogenetic manipulation of neural activity in C. elegans: From synapse to circuits and behaviour

The emerging field of optogenetics allows for optical activation or inhibition of excitable cells. In 2005, optogenetic proteins were expressed in the nematode Caenorhabditis elegans for the first time. Since then, C. elegans has served as a powerful platform upon which to conduct optogenetic investigations of synaptic function, circuit dynamics and the neuronal basis of behaviour. The C. elegans nervous system, consisting of 302 neurons, whose connectivity and morphology has been mapped completely, drives a rich repertoire of behaviours that are quantifiable by video microscopy. This model organism's compact nervous system, quantifiable behaviour, genetic tractability and optical accessibility make it especially amenable to optogenetic interrogation. Channelrhodopsin‐2 (ChR2), halorhodopsin (NpHR/Halo) and other common optogenetic proteins have all been expressed in C. elegans. Moreover, recent advances leveraging molecular genetics and patterned light illumination have now made it possible to target photoactivation and inhibition to single cells and to do so in worms as they behave freely. Here, we describe techniques and methods for optogenetic manipulation in C. elegans. We review recent work using optogenetics and C. elegans for neuroscience investigations at the level of synapses, circuits and behaviour.     

Biosystematic studies on the genus Heloniopsis (Melanthiaceae) I. Phylogeny inferred from plastid DNA sequences and taxonomic implications

Based on a combined dataset of plastid DNA sequences (atpB‐rbcL, trnG, trnL‐trnL‐trnF, trnK 5' intron and matK) from 60 individuals, we conducted parsimony and likelihood analyses to clarify the phylogenetic relationships among the six species and three varieties that are commonly recognised in Heloniopsis, in addition to the related genera Ypsilandra and Helonias, using Chamaelirium and Chionographis as an outgroup. According to the single most parsimonious tree, which was identical to the maximum‐likelihood tree in topology, Helonias, Ypsilandra and Heloniopsis are all monophyletic with 100% bootstrap support (BS). In Heloniopsis, there are two highly supported clades (BS 94–97%): a clade of Korean species and a clade of Japanese and Taiwanese species. The latter clade comprised the following four subclades (BS 99–100%): 1) H. orientalis var. orientalis, 2) H. orientalis var. breviscapa and var. flavida, 3) H. kawanoi and 4) H. leucantha and H. umbellata. Because subclades 1 and 2 did not form a monophyletic group, and do show clear morphological differences – including nectary position, nectary‐sac structure and leaf margin undulation – they should be distinguished at the species level: H. orientalis for subclade 1 and H. breviscapa for subclade 2. In subclade 2, neither var. breviscapa nor var. flavida was monophyletic; instead, var. breviscapa plus var. flavida (thick‐leaved entity) was monophyletic (BS 62–63%) and var. flavida (thin‐leaved entity) was monophyletic (BS 86–87%). As var. breviscapa and var. flavida (thick‐leaved entity) share basally ± pinkish wide tepals and dark‐coloured thick leaves, in contrast to var. flavida (thin‐leaved entity), which has completely white narrow tepals and light‐coloured thin leaves, the two varieties should may be kept distinct after the merge of var. flavida (thick‐leaved entity) with var. breviscapa.     

A new species of Laurencia, L. omaezakiana (Ceramiales, Rhodophyta), from Japan

Laurencia omaezakiana Masuda, sp. nov. (Ceramiales, Rhodophyta) is described from Japan. It is characterized by the following set of features: (i) the production of four periaxial cells from each vegetative axial cell; (ii) a shift in branching from distichous to spiral; (iii) the presence of projecting superficial cortical cells near the apices of branches; (iv) the presence of longitudinally oriented secondary pit-connections between contiguous superficial cortical cells; (v) the presence of lenticular thickenings in the walls of medullary cells; (vi) the occurrence of 1–2 corps en cerise in each superficial cortical cell and a single corps en cerise in each trichoblast cell; and (vii) a parallel arrangement of tetrasporangia. Furthermore, it produces a characteristic triterpenoid (enshuol), which has not been detected in other species of Laurencia, as a major halogenated secondary metabolite. A synoptical key to the 23 species of Laurencia growing in Japan is given. Laurencia ceytanica J, Agardh and Laurencia heteroclada Harvey are excluded from the Japanese marine algalflora. The latter is a distinct species from Laurencia filiformis (C. Agardh) Montagne.     

PHYLOGENETIC ANALYSIS OF EUDORINA SPECIES (VOLVOCACEAE,CHLOROPHYTA) BASED ON rbcL GENE SEQUENCES1

Species and varieties in the genus Eudorina Ehrenberg (Volvocaceae, Chlorophyta) were evaluated on the basis of phylogenetic analyses of the large subunit ofribulose-1,5-bis-phosphate carboxylase/oxygenase (rbcL) gene sequences from 14 strains of four Eudorina species, as well as from nine species of Pleodorina and Volvox. The sequence data suggested that 10 of the 14 Eudorina strains form three separate and robust monophyletic groups within the nonmonophyletic genus Eudorina. The first group comprises all three strains of E. unicocca G. M. Smith; the second group consists of one of the E. elegans Ehrenberg var. elegans strains, the E. cylindrica Korshikov strain, and both E. illinoisensis (Kofoid) Pascher strains; and the third group consists of two monoecious varieties of E. elegans [two strains of E. elegans var. synoica Goldstein and one strain of E. elegans var. carteri (G. M. Smith) Goldstein]. In addition, E. illinoisensis represents a poly- or paraphyletic species within the second group. The remaining four strains, all of which are assigned to E. elegans var. elegans, are nonmonophyletic. Although their position in the phylogenetic trees is more or less ambiguous, they are ancestral to other taxa in the large anisogamous/oogamous monophyletic group including Eudorina, Pleodorina, and Volvox (except for sect. Volvox). Thus, the four Eudorina groups resolved in the present molecular phylogeny do not correspond with the species concepts of Eudorina based on vegetative morphology, but they do reflect the results of the previous intercrossing experiments and modes of monoecious and dioecious sexual reproduction.     

Germ cell survival in C. elegans and C. remanei is affected when the dead box rna helicases Vbh‐1 or Cre‐VBH‐1 are silenced

The Vasa family of proteins comprises several conserved DEAD box RNA helicases important for mRNA regulation whose exact function in the germline is still unknown. In Caenorhabditis elegans, there are six known members of the Vasa family, and all of them are associated with P granules. One of these proteins, VBH‐1, is important for oogenesis, spermatogenesis, embryo development, and the oocyte/sperm switch in this nematode. We decided to extend our previous work in C. elegans to sibling species Caenorhabditis remanei to understand what is the function of the VBH‐1 homolog in this gonochoristic species. We found that Cre‐VBH‐1 is present in the cytoplasm of germ cells and it remains associated with P granules throughout the life cycle of C. remanei. Several aspects between VBH‐1 and Cre‐VBH‐1 function are conserved like their role during oogenesis, spermatogenesis, and embryonic development. However, Cre‐vbh‐1 silencing in C. remanei had a stronger effect on spermatogenesis and spermatid activation than in C. elegans. An unexpected finding was that silencing of vbh‐1 in the C. elegans caused a decrease in germ cell apoptosis in the hermaphrodite gonad, while silencing of Cre‐vbh‐1 in C. remanei elicited germ cell apoptosis in the male gonad. These data suggest that VBH‐1 might play a role in germ cell survival in both species albeit it appears to have an opposite role in each one. genesis 1–18 2012. © 2012 Wiley Periodicals, Inc.     

Putative calcium‐binding domains of the Caenorhabditis elegans BK channel are dispensable for intoxication and ethanol activation

Alcohol modulates the highly conserved, voltage‐ and calcium‐activated potassium (BK) channel, which contributes to alcohol‐mediated behaviors in species from worms to humans. Previous studies have shown that the calcium‐sensitive domains, RCK1 and the Ca²⁺ bowl, are required for ethanol activation of the mammalian BK channel in vitro. In the nematode Caenorhabditis elegans, ethanol activates the BK channel in vivo, and deletion of the worm BK channel, SLO‐1, confers strong resistance to intoxication. To determine if the conserved RCK1 and calcium bowl domains were also critical for intoxication and basal BK channel‐dependent behaviors in C. elegans, we generated transgenic worms that express mutated SLO‐1 channels predicted to have the RCK1, Ca²⁺ bowl or both domains rendered insensitive to calcium. As expected, mutating these domains inhibited basal function of SLO‐1 in vivo as neck and body curvature of these mutants mimicked that of the BK null mutant. Unexpectedly, however, mutating these domains singly or together in SLO‐1 had no effect on intoxication in C. elegans. Consistent with these behavioral results, we found that ethanol activated the SLO‐1 channel in vitro with or without these domains. By contrast, in agreement with previous in vitro findings, C. elegans harboring a human BK channel with mutated calcium‐sensing domains displayed resistance to intoxication. Thus, for the worm SLO‐1 channel, the putative calcium‐sensitive domains are critical for basal in vivo function but unnecessary for in vivo ethanol action.     

Proteomic Characterization of Caenorhabditis elegans Larval Development

The nematode Caenorhabditis elegans is widely used as a model organism to study cell and developmental biology. Quantitative proteomics of C. elegans is still in its infancy and, so far, most studies have been performed on adult worm samples. Here, we used quantitative mass spectrometry to characterize protein level changes across the four larval developmental stages (L1–L4) of C. elegans. In total, we identified 4130 proteins, and quantified 1541 proteins that were present across all four stages in three biological replicates from independent experiments. Using hierarchical clustering and functional ontological analyses, we identified 21 clusters containing proteins with similar protein profiles across the four stages, and highlighted the most overrepresented biological functions in each of these protein clusters. In addition, we used the dataset to identify putative larval stage‐specific proteins in each individual developmental stage, as well as in the early and late developmental stages. In summary, this dataset provides system‐wide analysis of protein level changes across the four C. elegans larval developmental stages, which serves as a useful resource for the C. elegans research community. MS data were deposited in ProteomeXchange ( http://proteomecentral.proteomexchange.org ) via the PRIDE partner repository with the primary accession identifier PXD006676.