Did trypanosomatid parasites have photosynthetic ancestors?

Some molecular phylogenies of plastid-like genes suggest that chloroplasts (the structures responsible for photosynthesis in plants and algae) might have been secondarily lost in trypanosomatid parasites. Chloroplasts are present in some euglenids, which are closely related to trypanosomatids, and it has been argued that chloroplasts arose early in the diversification of the lineage Euglenozoa, to which trypanosomatids and euglenids belong (plastids-early hypothesis). This article reviews how euglenid ultrastructural systems are functionally integrated and phylogenetically correlated. I argue that chloroplast acquisition profoundly altered the structure of certain euglenids, and that the complete absence of these modifications in other euglenozoans is most consistent with their never having had a chloroplast. Ultrastructural evidence suggests that chloroplasts arose relatively recently within a specific subgroup of euglenids and that trypanosomatids are not secondarily non-photosynthetic (plastids-recent hypothesis).     

Can the red mangrove provide food,feed and fertilizer?

The red mangrove is one of the principal features of the coastal vegetation throughout tropical America, Mexico, the West Indies, the Bahamas, Bermuda and southern Florida. It is of primary importance as a land retainer and builder. Secondarily, its bark is a source of tannin and yields resins suitable for plywood adhesive. Mangrove wood is heavy and durable. The bark, leaves and shoots furnish various dyes and the bark is an excellent fuel and is much used locally for medicinal purposes. In southern Florida there has been active interest in the value of mangrove leaf meal as cattle feed, the dried and ground leaves have been sold as “Maritime Tea” and prepared in tablet form as a dietary supplement. The leaf meal and the sawdust have been tested as soil conditioners. Despite their high tannin content, red mangrove leaves may warrant investigation as an abundant source of protein.     

Did the evolution of the phytoplankton fuel the diversification of the marine biosphere?

We discuss the possible links between the fossil record of marine biodiversity, nutrient availability and primary productivity. The parallelism of the fossil records of marine phytoplankton and faunal biodiversity implicates the quantity (primary productivity) and quality (stoichiometry) of phytoplankton as being critical to the diversification of the marine biosphere through the Phanerozoic. The relatively subdued marine biodiversity of the Palaeozoic corresponds to a time of relatively low macronutrient availability and poor food quality of the phytoplankton as opposed to the diversification of the Modern Fauna through the Mesozoic–Cenozoic. Increasing nutrient runoff to the oceans through the Phanerozoic resulted from orogeny, the emplacement of Large Igneous Provinces (LIPs), the evolution of deep-rooting forests and the appearance of more easily decomposable terrestrial organic matter that enhanced weathering. Positive feedback by bioturbation of an expanding benthos played a critical role in evolving biogeochemical cycles by linking the oxidation of dead organic matter and the recycling of nutrients back to the water column where they could be re-utilized. We assess our conclusions against a recently published biogeochemical model for geological time-scales. Major peaks of marine diversity often occur near rising or peak fluxes of silica, phosphorus and dissolved reactive oceanic phosphorus; either major or minor ⁸⁷Sr/⁸⁶Sr peaks; and frequently in the vicinity of major (Circum-Atlantic Magmatic Province) and minor volcanic events, some of which are associated with Oceanic Anoxic Events. These processes appear to be scale-dependent in that they lie on a continuum between biodiversification on macroevolutionary scales of geological time and mass extinction.     

Systems biology and the origins of life? Part I. Are biochemical networks possible ancestors of living systems? Reproduction,identity and sensitivity to signals of biochemical networks

The set of these two theoretical papers offers an alternative to the hypothesis of a primordial RNA-world. The basic idea of these papers is to consider that the first prebiotic systems could have been networks of catalysed reactions encapsulated by a membrane. In order to test this hypothesis it was attempted to list the main obligatory features of living systems and see whether encapsulated biochemical networks could possibly display these features. The traits of living systems are the following: the ability they have to reproduce; the fact they possess an identity; the fact that biological events should be considered in the context of a history; the fact that living systems are able to evolve by selection of alterations of their structure and self-organization. The aim of these two papers is precisely to show that encapsulated biochemical networks can possess these properties and can be considered good candidates for the first prebiotic systems. In the present paper it is shown that if the proteinoids are not very specific catalysts and if some of the reactions of the network are autocatalytic whereas others are not, the resulting system does not reach a steady-state and tends to duplicate. In the same line, these biochemical networks possess an identity, viz. an information, defined from the probability of occurrence of these nodes. Moreover interaction of two ligands can increase, or decrease, this information. In the first case, the system is defined as emergent, in the second case it is considered integrated. Another property of living systems is that their behaviour is defined in the context of a time-arrow. For instance, they are able to sense whether the intensity of a signal is reached after an increase, or a decrease. This property can be mimicked by a simple physico-chemical system made up of the diffusion of a ligand followed by its chemical transformation catalysed by a proteinoid displaying inhibition by excess substrate. Under these conditions the system reacts differently depending on whether the same ligand concentration is reached after an increase or a decrease.     

Did maize domestication and early spread mediate the population genetics of corn leafhopper?

Investigating how crop domestication and early farming mediated crop attributes, distributions, and interactions with antagonists may shed light on today's agricultural pest problems. Crop domestication generally involved artificial selection for traits desirable to early farmers, for example, in creased productivity or yield, and enhanced qualities, though invariably it altered the interactions between crops and insects, and expanded the geographical ranges of crops. Thus, some studies suggest that with crop domestication and spread, insect populations on wild crop ancestors gave rise to pestiferous insect populations on crops. Here, we addressed whether the emergence of corn leafhopper (Dalbulus ma id is) as an agricultural pest may be associated with domestication and early spread of maize (Zea mays mays). We used AFLP markers and mitochondrial COI sequences to assess population genetic structuring and haplotype relationships among corn leafhopper samples from maize and its wild relative Zea diploperennis from multiple locations in Mexico and Argentina. We uncovered seven corn leafhopper haplotypes contained within two haplogroups, one haplogroup containing haplotypes associated with maize and the other containing haplotypes associated with Z. diploperennis in a mountainous habitat. Within the first haplogroup, one haplotype was predominant across Mexican locations, and another across Argentinean locations;both were considered pestiferous. We suggested that the divergence times of the maize-associated haplogroup and of the "pestiferous" haplotypes are correlated with the chronology of maize spread following its domestication. Overall, our results support a hypothesis positing that maize domestication favored corn leafhopper genotypes preadapted for exploiting maize so that they became pestiferous, and that with the geographical expansi on of maize farming, corn leafhopper colonized Z. diploperennis, a host exclusive to secluded habitats that serves as a refuge for archaic corn leafhopper genotypic diversity. Broadly, our results help explain the extents to which crop domestication and early spread may have mediated the emergence of today's agricultural pests.     

Did the ancestral globin gene of plants and animals contain only two introns?

All vertebrate globin genes contain two introns, while plant globin genes contain three. It is widely thought that the plant gene structure reflects the structure of the primordial globin gene and that a common ancestor of all animals lost the central intron shortly after the divergence of plants and animals more than one billion years ago. The recent discovery of a discordant central intron in some animal globin genes suggests that this model is incorrect. We propose that the typical vertebrate two-intron gene structure is the primordial eukaryotic form, and that following the distructure is the primordial eukaryotic form, and that following the divergence of plants and animals, a common ancestor of plants gained a central intron in the globin gene.     

Did circular DNA shape the evolution of mammalian genomes?

Extrachromosomal circular DNA (eccDNA) can shape the genomes of somatic cells, but how it impacts genomes across generations is largely unexplored. We propose that genomes can rearrange via circular intermediates across generations and show that up to 6% of a mammalian genome can have changed gene order through eccDNA.     

Did Vaccination Slow the Spread of Bluetongue in France?

Vaccination is one of the most efficient ways to control the spread of infectious diseases. Simulations are now widely used to assess how vaccination can limit disease spread as well as mitigate morbidity or mortality in susceptible populations. However, field studies investigating how much vaccines decrease the velocity of epizootic wave-fronts during outbreaks are rare. This study aimed at investigating the effect of vaccination on the propagation of bluetongue, a vector-borne disease of ruminants. We used data from the 2008 bluetongue virus serotype 1 (BTV-1) epizootic of southwest France. As the virus was newly introduced in this area, natural immunity of livestock was absent. This allowed determination of the role of vaccination in changing the velocity of bluetongue spread while accounting for environmental factors that possibly influenced it. The average estimated velocity across the country despite restriction on animal movements was 5.4 km/day, which is very similar to the velocity of spread of the bluetongue virus serotype 8 epizootic in France also estimated in a context of restrictions on animal movements. Vaccination significantly reduced the propagation velocity of BTV-1. In comparison to municipalities with no vaccine coverage, the velocity of BTV-1 spread decreased by 1.7 km/day in municipalities with immunized animals. For the first time, the effect of vaccination has been quantified using data from a real epizootic whilst accounting for environmental factors known to modify the velocity of bluetongue spread. Our findings emphasize the importance of vaccination in limiting disease spread across natural landscape. Finally, environmental factors, specifically those related to vector abundance and activity, were found to be good predictors of the velocity of BTV-1 spread, indicating that these variables need to be adequately accounted for when evaluating the role of vaccination on bluetongue spread.     

Did biological control cause extinction of the coconut moth, Levuana iridescens, in Fiji?

In 1925, J.D. Tothill and two colleagues set out to manage Levuana iridescens, the coconut moth of Fiji, using biological control. By 1930, they had succeeded so completely that this pest of the copra crop had been reduced to almost undetectable levels by the tachinid fly, Bessa remota, introduced from Malaya, and they had summarized their campaign in a thoroughly documented and well-illustrated monograph. The example of the coconut moth is presented in the modern literature as the first and best documented extinction of a species due to scientific biological control. The program has been severely criticized because the moth was unique, beautiful, and considered endemic to Fiji. Thus, this program is also portrayed as an example of the highly controversial practice of neoclassical biological control. However, a careful reexamination of this event discloses that the moth was likely not native to Fiji, appeared to be spreading through the Fijian Archipelago, and might have spread to other island groups in the South Pacific. Also, L. iridescens is probably not extinct. Collateral damage, that is, non-target impacts, did occur as native zygaenid moths have been attacked by the tachinid, and they may be extinct. The reasons for the control campaign of L. iridescens were not primarily economic. Tothill and colleagues were trying to protect copra so that ethnic Fijian culture, so dependent on the coconut palm threatened by L. iridescens, could be sustained. Hence, this control program represents a difficult clash of values: preservation of insect biodiversity versus preservation of indigenous Pacific Islander cultures. A strategy to search for L. iridescens populations is proposed and development of biological control of B. remota, using hyperparasitoids, is possible, but would require careful evaluation since it might release L. iridescens from suppression, have non-target impacts on native tachinids, and lack an economic motivation.     

Did the Quaternary climatic fluctuations really influence the tempo and mode of diversification in European rodents?

The objective of this study was to establish whether the Quaternary climatic fluctuations influenced the tempo and mode of diversification in European rodents. Our case study is the subgenus Microtus (Terricola) distributed from western Europe to the Caucasus. Mitochondrial cytochrome b gene sequences from several representatives of all the species were used to generate maximum‐likelihood and Bayesian phylogenetic trees, to estimate divergence times, to identify biogeographic ancestral areas and to study the rate of diversification. Results showed that phylogenetic tree topologies were similar to previous published studies but with a better resolution at some nodes. The origin of Microtus (Terricola) is dated back to approximately 4.05 Myr in the Early Pliocene, and molecular dating for most Terricola species corresponds to several glacial periods of the Pleistocene. Results of the biogeographic ancestral area reconstruction suggest that Microtus (Terricola) diversified from the Caucasus/Turkey/Iran area through western Europe. Several periods of diversity variation were highlighted as follows: two period of diversity increase, between 3 and 2 Myr, and after 1 Myr; two periods of diversity decrease, before 3 Myr, and between 2 and 1 Myr. The diversification rate of Microtus (Terricola) was 0.353 ± 0.004 event/Myr, a rate similar to that of the Muridae family. To conclude, although the Pleistocene glacial conditions had an impact on the speciation events, the Quaternary does not appear however as a period with an exceptional rate of diversification for European rodents.     

Cambrian lobopodians–ancestors of extant onychophorans?

This paper is a review of published information on fossil lobopodians, with addition of observations and ideas based on new material. It is also an analysis of the phytogeny of the group, and presents a new classification. A character shared by three or four families, yet not seen before, is a pair of enlarged sclerites covering the head. This forms an argument for re-orienting Hallucigenia once again. This genus no longer being enigmatic, a corner-stone in Stephen Jay Gould's evidence for extinct phyla is therefore gone. It is suggested that the lobopodians, phylum Lobopodia, are arranged in two classes, the extinct Xenusia for marine forms, and the Onychophora for terrestrial forms. The marine lobopodians are morphologically much more diverse than the extant onychophorans, a condition expressed in the classification. New taxa are: Hallucigenia fortis sp. nov., the families Luolishaniidae, Cardiodictyidae and Onychodictyidae, and the new orders Archonychophora, Scleronychophora and Paronychophora.     

Octopamine in leeches—II. Synthesis,release and reuptake of octopamine by the ventral nerve cord of Erpobdella octoculata

1. Octopamine was synthesized by the ventral nerve cords of E. octuculata during in vitro incubation in radiolabelled tyrosine and tyramine. Trace amounts of dopamine were also synthesized from tyrosine and tyramine.2. In vitro uptake of ³H-octopamine revealed the presence of a sodium sensitive and a sodium insensitive component which was linear up to 10.54 μM. The sodium sensitive component showed at least one component that was fully saturated at 1.54 μM octopamine, possessed a K_m of approximately 4 × 10⁻⁷ M and a V_max of 15.5 mM/10 ventral nerve cord ganglia/min.3. Release of preloaded ³H-octopamine from ventral nerve cords was by a calcium-dependent process. A high-potassium-induced calcium-dependent release was also demonstrated.4. Hydroxymandelic acid production was decreased in the presence of iproniazid phosphate suggesting the presence of a monoamine oxidase.5. The synthesis, release, reuptake and metabolism of octopamine are discussed in the light of octopamine as a central transmitter in the leech.     

Diversity and Abundance of the Bacterial Community of the Red Macroalga Porphyra umbilicalis: Did Bacterial Farmers Produce Macroalgae?

Macroalgae harbor microbial communities whose bacterial biodiversity remains largely uncharacterized. The goals of this study were 1) to examine the composition of the bacterial community associated with Porphyra umbilicalis Kützing from Schoodic Point, ME, 2) determine whether there are seasonal trends in species diversity but a core group of bacteria that are always present, and 3) to determine how the microbial community associated with a laboratory strain (P.um.1) established in the presence of antibiotics has changed. P. umbilicalis blades (n = 5, fall 2010; n = 5, winter 2011; n = 2, clonal P.um.1) were analyzed by pyrosequencing over two variable regions of the 16 S rDNA (V5–V6 and V8; 147,880 total reads). The bacterial taxa present were classified at an 80% confidence threshold into eight phyla (Bacteroidetes, Proteobacteria, Planctomycetes, Chloroflexi, Actinobacteria, Deinococcus-Thermus, Firmicutes, and the candidate division TM7). The Bacteroidetes comprised the majority of bacterial sequences on both field and lab blades, but the Proteobacteria (Alphaproteobacteria, Gammaproteobacteria) were also abundant. Sphingobacteria (Bacteroidetes) and Flavobacteria (Bacteroidetes) had inverse abundances on natural versus P.um.1 blades. Bacterial communities were richer and more diverse on blades sampled in fall compared to winter. Significant differences were observed between microbial communities among all three groups of blades examined. Only two OTUs were found on all 12 blades, and only one of these, belonging to the Saprospiraceae (Bacteroidetes), was abundant. Lewinella (as 66 OTUs) was found on all field blades and was the most abundant genus. Bacteria from the Bacteroidetes, Proteobacteria and Planctomycetes that are known to digest the galactan sulfates of red algal cell walls were well-represented. Some of these taxa likely provide essential morphogenetic and beneficial nutritive factors to P. umbilicalis and may have had unexpected effects upon evolution of macroalgal form as well as function.     

Seed ferns from the late Paleozoic and Mesozoic: Any angiosperm ancestors lurking there?

Five orders of late Paleozoic-Mesozoic seed ferns have, at one time or another, figured in discussions on the origin of angiosperms, even before the application of phylogenetic systematics. These are the Glossopteridales, Peltaspermales, Corystospermales, Caytoniales, and Petriellales. Although vegetative features have been used to suggest homologies, most discussion has focused on ovulate structures, which are generally interpreted as megasporophylls bearing seeds, with the seeds partially to almost completely enclosed by the megasporophyll (or cupule). Here we discuss current information about the reproductive parts of these plants. Since most specimens are impression-compression remains, homologizing the ovulate organs, deriving angiospermous homologues, and defining synapomorphies remain somewhat speculative. Although new specimens have increased the known diversity in these groups, a reconstruction of an entire plant is available only for the corystosperms, and thus hypotheses about phylogenetic position are of limited value. We conclude that, in the case of these seed plants, phylogenetic analysis techniques have surpassed the hard data needed to formulate meaningful phylogenetic hypotheses. Speculation on angiosperm origins and transitional stages in these fossils provides for interesting discussion, but currently it is still speculation, as the role of these groups in the origin of angiospermy continues to be cloaked in Darwin's mystery.     

Did the molecules of adaptive immunity evolve from the innate immune system?

The antigen receptors on cells of innate immune systems recognizebroadly expressed markers on non-host cells while the receptorson lymphocytes of the adaptive immune system display a higherlevel of specificity. Adaptive immunity, with its exquisitespecificity and immunological memory, has only been found inthe jawed vertebrates, which also display innate immunity. Jawlessfishes and invertebrates only have innate immunity. In the adaptiveimmune response, T and B-lymphocytes detect foreign agents orantigens using T cell receptors (TCR) or immunoglobulins (Ig),respectively. While Ig can bind free intact antigens, TCR onlybinds processed antigenic fragments that are presented on moleculesencoded in the major histocompatibility complex (MHC). MHC moleculesdisplay variation through allelic polymorphism. A diverse repertoireof Ig and TCR molecules is generated by gene rearrangement andjunctional diversity, processes carried out by the recombinaseactivating gene (RAG) products and terminal deoxynucleotidyltransferase (TdT). Thus, the molecules that define adaptiveimmunity are TCR, Ig, MHC molecules, RAG products and TdT. Nodirect predecessors of these molecules have been found in thejawless fishes or invertebrates. In contrast, the complementcascade can be activated by either adaptive or innate immunesystems and contains examples of molecules that gradually evolvedfrom non-immune functions to being part of the innate and thenadaptive immune system. In this paper we examine the moleculesof the adaptive immune system and speculate on the existenceof direct predecessors that were part of innate immunity.     

Did the introduction of maize into Europe provide enemy‐free space to Ostrinia nubilalis? Parasitism differences between two sibling species of the genus Ostrinia

We examined whether maize offers enemy‐free space (EFS) to its pest Ostrinia nubilalis, and may thereby have contributed to its divergence from the sibling species, Ostrinia scapulalis, feeding mainly on mugwort, when introduced into Europe five centuries ago. We collected Ostrinia larvae on maize (70 populations, 8425 individuals) and mugwort (10 populations, 1184 individuals) and recorded parasitism using both traditional (counting emerging parasitoids) and molecular methods (detection by specific polymerase chain reaction). The main parasitoid was Macrocentrus cingulum (Braconidae). On mugwort, parasitism was twice that on maize, and parasitoid‐related mortality was 8 times higher. This suggests that maize affords substantial EFS to Ostrinia feeding on it. The lower Mortality:Infestation ratio in maize suggests that O. nubilalis’ immune response might be stronger than that of O. scapulalis. If so, adapting to maize and diverging from O. scapulalis would decrease the impact of parasitism on O. nubilalis at both ecological and evolutionary levels.     

Did Native Americans influence the northward migration of plants during the Holocene?

Abstract Long‐distance plant dispersal explains the rapid northward migration of plant species during the Holocene but the mechanisms by which it occurred are poorly understood. Given that Native Americans spread numerous cultigens over thousands of kilometres during the late Holocene, I examined historical literature for evidence of non‐cultigen dispersal or cultivation in North America's eastern woodlands. Cultivation references are included because a strong relationship between dispersal and indigenous flora husbandry is assumed. Sixty‐seven texts describing Native American lifestyle, cultural activities, and land management reported some form of plant use. Most accounts, however, focus on cultigen production or the use of indigenous flora for medicine or food without mention of dispersal. Twenty‐four of the texts described the trade, transport, or cultivation of plants indigenous to eastern North American woodlands. Most accounts focus on the informal production of food plants, especially trees and shrubs. Confounding these reports was clear evidence of observer bias, limited botanical knowledge, acculturation, and secrecy by Native American informants. Because of these shortcomings, the likelihood of widespread long‐distance plant dispersal by Native Americans could not be determined using historical literature. This activity was either not widespread or was not observed by, or revealed to, Europeans. To adequately test the Native American plant dispersal hypothesis, direct evidence from other sources (e.g. archaeobotancial data) will be required.