Molecular phylogeny of Megaloceros giganteus--the giant deer or just a giant red deer?

Two fragments of mitochondrial DNA (mtDNA) of the cytochrome b gene (137 bp and 167 bp) were successfully isolated and sequenced from antlers and bones of five specimens of the Giant Deer (Megaloceros giganteus) to examine the phylogenetic position of Megaloceros giganteus within the family Cervidae. This is the first report on ancient DNA (aDNA) sequences from Megaloceros giganteus. A phylogenetic analysis based on parameter-rich models describes the evolutionary relationships between five individuals of fossil Megaloceros giganteus and 37 individuals of 11 extant species of the family Cervidae. The results support a "Cervus-Megaloceros" clade. The phylogenetic positions of sympatric Megaloceros and Cervus elaphus specimens in particular indicate either that the Megaloceros mtDNA gene pool did not evolve for a substantial time period as an entity distinct from Cervus elaphus until its extinction, or that Megaloceros contributed mtDNA to Cervus elaphus or vice versa. The results of this study allow the conclusion that the European Megaloceros giganteus is more related to its modern regional counterparts of the species of Cervus elaphus than recent claims have suggested.     

Phylogeography and history of giant Galápagos tortoises

Abstract.— We examined the phylogeography and history of giant Galàpagos tortoise populations based on mito-chondrial DNA sequence data from 161 individuals from 21 sampling sites representing the 11 currently recognized extant taxa. Molecular clock and geological considerations indicate a founding of the monophyletic Galàpagos lineage around 2–3 million years ago, which would allow for all the diversification to have occurred on extant islands. Founding events generally occurred from geologically older to younger islands with some islands colonized more than once. Six of the 11 named taxa can be associated with monophyletic maternal lineages. One, Geochelone porteri on Santa Cruz Island, consists of two distinct populations connected by the deepest node in the archipelago-wide phylogeny, whereas tortoises in northwest Santa Cruz are closely related to those on adjacent Pinzón Island. Volcan Wolf, the northernmost volcano of Isabela Island, consists of both a unique set of maternal lineages and recent migrants from other islands, indicating multiple colonizations possibly due to human transport or multiple colonization and partial elimination through competition. These genetic findings are consistent with the mixed morphology of tortoises on this volcano. No clear genetic differentiation between two taxa on the two southernmost volcanoes of Isabela was evident. Extinction of crucial populations by human activities confounds whether domed versus saddleback carapaces of different populations are mono- or polyphyletic. Our findings revealed a complex phylogeography and history for this tortoise radiation within an insular environment and have implications for efforts to conserve these endangered biological treasures.     

Sensory ecology: giant eyes for giant predators?

Mathematical models suggest the enormous eyes of giant and colossal squid evolved to see the bioluminescence induced by the approach of predatory whales.     

Pharmacological characteristics of four giant neurons identified in the cerebral ganglia of an African giant snail (Achatina fulica Férussac)

Two giant neurons, d-RCDN (dorsal-right cerebral distinct neuron) and d-LCDN (dorsal left cerebral distinct neuron), with a diameter of about 100 microns, were found symmetrically on the dorsal surface of the cerebral ganglia of an African giant snail (Achatina fulica Férussac). They showed spontaneous spike discharges at a stable frequency. Two giant neurons, v-RCDN (ventral-right cerebral distinct neuron) and v-LCDN (ventral-left cerebral distinct neuron), (diameter, approx. 150 microns) were identified on the ventral surface of the same ganglia. No spontaneous spike discharges were evident. Both d-RCDN and d-LCDN were equally inhibited by dopamine, octopamine, 5-hydroxytryptamine and histamine. Acetylcholine sometimes showed inhibitory effects, but they were not so stable. No substance having excitatory effects on the neurons was found. Both v-RCDN and v-LCDN were equally excited by octopamine, 5-hydroxytryptamine, GABA and acetylcholine and inhibited by dopamine and beta-hydroxy-L-glutamic acid.     

Microsatellite analysis of genetic divergence among populations of giant Galápagos tortoises

Giant Galápagos tortoises represent an interesting model for the study of patterns of genetic divergence and adaptive differentiation related to island colonization events. Recent mitochondrial DNA work elucidated the evolutionary history of the species and helped to clarify aspects of nomenclature. We used 10 microsatellite loci to assess levels of genetic divergence among and within island populations. In particular, we described the genetic structure of tortoises on the island of Isabela, where discrimination of different taxa is still subject of debate. Individual island populations were all genetically distinct. The island of Santa Cruz harboured two distinct populations. On Isabela, populations of Volcan Wolf, Darwin and Alcedo were significantly different from each other. On the other hand, Volcan Wolf showed allelic similarity with the island of Santiago. On Southern Isabela, lower genetic divergence was found between Northeast Sierra Negra and Volcan Alcedo, while patterns of gene flow were recorded among tortoises of Cerro Azul and Southeast Sierra Negra. These tortoises have endured heavy exploitation during the last three centuries and recently attracted much concern due to the current number of stochastic and deterministic threats to extant populations. Our study complements previous investigation based on mtDNA diversity and provides further information that may help devising tortoise management plans.     

Can giant chlorosomes be part of the light-harvesting antennae of green bacteria?

Some data on the structure and composition of chlorosomes are in conflict with their energy and kinetic characteristics. Among the latter is the very short excitation lifetime of the dominant pigment C740 in the 3D giant chlorosome (about 1000 pigment molecules per reaction center). Therewith the excitation transfer from C740 to baseplate bacteriochlorophyll B795 and further to the main membrane B860 can hardly be efficient. This result was obtained by modeling the energy migration between these pigment fractions in maximally optimized conditions. The possible reasons and mechanisms responsible for such strong nonphotochemical quenching of electronic excitations in the pigments of giant chlorosomes are substantiated and discussed.     

Effects of synthetic peptides on giant neurons identified in the ganglia of an African giant snail (Achatina fulica Férussac)--II

Thirteen synthetic biologically-active peptides, which were classified into the peptides proposed as neurotransmitters in mammals and invertebrates and neural venom peptides, were investigated for their effects on the following six identifiable giant neurons of an African giant snail (Achatina fulica Férussac): RAPN (right anterior pallial neuron), INN (intestinal nerve neuron), RPeNLN (right pedal nerve large neuron), LPeNLN (left pedal nerve large neuron), d-LPeLN (dorsal-left pedal large neuron) and d-LPeCN (dorsal-left pedal constantly firing neuron). Oxytocin and proctolin at 10(-4)M excited the RAPN membrane potential, whereas FMRFamide at the same concentration inhibited the same neuron. FMRFamide at 10(-4)M markedly inhibited the d-LPeLN membrane potential, sometimes produced inhibition of RPeNLN and LPeNLN, showed varied effects (excitatory or inhibitory) on INN, and had no effect on d-LPeCN. The other peptides examined had almost no effect on any of the neurons tested.     

Evolutionary conservation of the 3′ ends of members of a family of giant secretory protein genes inChironomus pallidivittatus

Summary Two cDNA clones representing the 3-end regions of BR1 and BR2 75S mRNA were obtained fromChironomus pallidivittatus. The regular structure characterizing the core of these genes, consisting of tandemly arranged repeat units, changes into a more irregular structure toward the 3 end. Distal to a standard type of repeat unit with a characteristic excess of positive charges, a new type of repeat with a high, negative charge density is interspersed among parts of the standard unit. The last 111 amino acids before the stop codon represent a unique region distinctly different in amino acid composition from upstream regions, and include two partially homologous hydrophobic regions. Sequence comparison of 3-end regions from clones representing BR1 and BR2 genes indicates striking sequence conservation in the unique part of the region. Analysis of the level of silent site divergence shows that the homology increases in the 3 direction up to the polyadenylation site. That the unique region is retained as a part of the secreted protein is shown by Western blotting.     

Properties of sodium and potassium channels of the squid giant axon far below 0°C

Summary Squid giant axon could be excited in concentrated glycerol solutions containing normal concentrations of electrolytes, when osmolalities of solutions inside and outside the axon were matched. These glycerol solutions did not freeze at the temperature as low as –19°C. The nerve excitation in these solutions were observed at this low temperature. The excitation process at this low temperature was slowed down and time constants of the excitation kinetics were several hundredfold larger than those in normal seawater at 10°C, under which temperature the squid habituated. The temperature coefficients for the electrophysiological membrane parameters under this condition were larger than those in normal seawater above 0°C. The Q₁₀ value for the conduction velocity was 2.0 and that of the duration of the action potential was around 8.5. The time course of the membrane currents was also slowed with the Q₁₀ value of around 5 and the magnitude decreased with the Q₁₀ value of around 2 as the temperature was lowered. The Q₁₀ values for the kinetics of the on process of the Na-channel were around 4.5 and were almost the same as those of the off process of the Na-channel in the wide range of the temperature below 0°C. The Q₁₀ value of the on process of K-channel was around 6.5 and was larger than those for Na-channel. The Q₁₀ values increased gradually as the temperature was lowered.     

Genetic analysis of a successful repatriation programme: giant Galápagos tortoises

As natural populations of endangered species dwindle to precarious levels, remaining members are sometimes brought into captivity, allowed to breed and their offspring returned to the natural habitat. One goal of such repatriation programmes is to retain as much of the genetic variation of the species as possible. A taxon of giant Galápagos tortoises on the island of Espa?ola has been the subject of a captive breeding-repatriation programme for 33 years. Core breeders, consisting of 12 females and three males, have produced more than 1200 offspring that have been released on Espa?ola where in situ reproduction has recently been observed. Using microsatellite DNA markers, we have determined the maternity and paternity of 132 repatriated offspring. Contributions of the breeders are highly skewed. This has led to a further loss of genetic variation that is detrimental to the long-term survival of the population. Modifications to the breeding programme could alleviate this problem.     

The effect of amino acids on the excitability of identified autoactive giant neurons of Achatina fulica Férussac]

Effects of the following amino acids were examined on the electrical activity of the two giant neurones (PON and TAN) identified in the subesophageal ganglia of Achatina fulica Férussac : L-Asp, L-Thr, L-Ser, L-Glu, L-Pro, Gly, L-alpha-Ala, beta-Ala, L-cysteine, L-cystine, L-Val, L-Met, L-Ileu, L-Leu, L-Tyr, L-Phe, L-Lys, L-His, L-Arg, L-Cit, L-Try, GABA and GABOB. Among these substances, we observed an inhibitory effect of GABA and GABOB on the TAN excitability. GABA showed stronger effect on the TAN than GABOB. This effect of GABA was due to producing hyperpolarization on the TAN membrane. GABA showed a slight excitatory effect on the PON. The effect of GABOB on the PON was very weak and unstable.     

Research of a holiday kind: One giant leap for mankind? A cost-utility analysis of abolishing the law of gravity

Background

Canada''s Neo Rhino Party, a joke political party created in 2006 as a successor to the Parti Rhinocéros, is planning a new regulation to repeal the law of gravity, which could have an important impact on diseases attributable to gravity on earth.

Methods

We sought to estimate the number of quality-adjusted life-years that would be saved if the proposed regulation is passed and determine the cost-effectiveness of adapting Boris Volfson''s antigravity machine¹ for use on earth. We performed an economic analysis using a hidden Markov model.

Results

Our results suggest that a microgravity environment would save over 2 million quality-adjusted life-years. The cost for every quality-adjusted life-year saved is estimated to be $328.

Interpretation

Microgravity is the solution to the health care crisis in Canada. In addition, using technological, statistical and medical jargon gives us the opportunity to defy the laws of physics, mathematics and medicine.Canada''s Neo Rhino Party is a joke federal political party that was created in Montréal, Quebec, in 2006 as the successor to the Parti Rhinocéros. Commonly called the Rhinoceros Party in English, this party was a registered political party in Canada from the 1960s to the 1990s. It was founded in 1963 by Jacques Ferron, a Canadian physician and author. The party''s basic credo was “a promise to keep none of our promises.” Its election platforms comprised impossible schemes that were designed to amuse and entertain the voting public. Some Rhinoceros Party promises included reducing the speed of light because it''s much too fast, paving Manitoba to create the world''s largest parking lot, providing higher education by building taller schools and repealing the law of gravity. When this last promise was made in the 1980s, it was unthinkable, that is, until Boris Volfson of Huntington, Indiana, received US Patent 6 960 975 for his design of an antigravity machine.¹ The Neo Rhino Party is currently planning a new regulation to repeal the law of gravity that could have an important impact on diseases and other health outcomes attributable to gravity on earth.     

Does a giant tortoise taxon substitute enhance seed germination of exotic fleshy-fruited plants?

Aims The use of exotic species as taxon substitutes to restore lost ecological interactions is currently hotly debated. Aldabrachelys gigantea giant tortoises have recently been introduced to three islands in the Mascarene archipelago (Ile aux Aigrettes, Round Island and Rodrigues) to resurrect herbivory and seed dispersal functions once performed by extinct giant tortoises. However, potential unintended impacts by frugivore substitutes on native ecosystems, e.g. whether they will facilitate the germination of exotic plant species, are largely unknown. We investigated whether A. gigantea introduced to Rodrigues in 2006 could enhance the germination percentage of four widespread fleshy-fruited exotic species on the island. Using germination trials to forecast unintended impacts that could arise from the introduction of a frugivorous taxon substitute enables conservation managers to limit potential adverse negative interactions before they occur.Methods In germination trials that ran over 4 months, we investigated the effects of ingestion (gut passage and deposition in faeces) by sub-adult and adult A. gigantea on the germination percentage of four exotic fleshy-fruited plant species introduced to Rodrigues. We fed fruits of these plant species to sub-adult and adult A. gigantea to test how variation in age and size of the frugivore would affect seed germination. Feeding of distinctly coloured plastic pellets together with the fruits allowed us to test for individual tortoise effects on seed germination.Important findings Ingestion by A. gigantea increased the percentage of seeds germinating of Mimusops coriacea and Lantana camara, but not percentage of germination of Veitchia merrillii or Wikstroemia indica. Seeds were more likely to germinate following ingestion by sub-adult rather than adult tortoises, which may be a consequence of the shorter gut passage time observed for sub-adults. Our results demonstrate that introduced frugivorous taxon substitutes could facilitate germination of exotic and invasive plants and highlight the need for conservation managers to weigh the risk of taxon substitutes potentially facilitating the germination and recruitment of exotic fleshy-fruited plants against the benefit of restoring lost seed dispersal functions of threatened indigenous plants. Our findings also highlight the importance of considering age and size variation in frugivores, in particular in long-lived taxa such as giant tortoises, when studying ingestion effects on the germination performance of plants.     

Effect of supercooling and freezing on photosynthesis in freezing tolerant leaves of Afroalpine ‘giant rosette’ plants

Summary The effect of supercooling and freezing on the photosynthetic capability of representatives of the permanent frost hardy giant rosette plants Dendrosenecio keniodendron, D. brassica and Lobelia telekii, of the tropical alpine regions was investigated with the non-invasive chlorophyll a fluorescence technique. While supercooling, normal chlorophyll a fluorescence kinetics exhibiting the sequence 0, I, (D), P, S, M, were recorded, however with some retardation of both, the fast and the slow characteristics as compared to those obtained at day-time temperature. As long as the leaves remained unfrozen, the rise of the variable fluorescence F from the level 0 to P was inversely related to a drop of the temperature from about 0°C to-8°C. The increase of F with lower temperature is understood to result from a decrease of the velocity of the quenching reactions while photoreduction of the primary electron acceptor appeared to be unimpeded. The second fluorescence maximum (M), usually interpreted to indicate the commencement of the biochemical reactions of photosynthesis was consistenly to be observed during supercooling. Fluoescence induction kinetics of frozen leaves showed only fast rise to presumably F _max which was not followed by a significant decay for as long as 4 min. The lack of substantial quenching indicates that in the freeze-dehydrated state neither reoxidation of the primary acceptor nor energetization of the thylakoid membrane was accomplished. This effect however was immediately and fully reserved upon thawing of the leaves when the usual fluorescence induction kinetics as well as normal rates of CO₂-uptake were observed. Thus the permanent frost-hardy afroalpine plants do not exhibit any even short-term memory effect of the nocturnal frost on such a delicate process as is photosynthesis.     

Histological and pharmacological investigations of the two symmetrically situated giant neurons, RPeNLN and LPeNLN, identified on the anterior surface of the pedal ganglia of an African giant snail (Achatina fulica Férussac)

Morphological and pharmacological investigations were made of two giant neurons, RPeNLN (right pedal nerve large neuron) and LPeNLN (left pedal nerve large neuron), situated symmetrically on the anterior surface of the pedal ganglia of an African giant snail (Achatina fulica Férussac). The two neurons (about 250-300 microns in diameter) were the largest ones identified in the ganglia of the snail species. The axonal pathways of the two neurons were symmetrical; of their four main axonal branches, the three main branches innervated the ipsilateral pedal nerves, whereas the last main branch projected to the contralateral pedal nerves. The pharmacological features of the two neurons were very similar. Both were inhibited markedly by dopamine [minimum effective concentrations (MECs): 3 X 10(-6)-10(-5) M], DL-octopamine (MECs: 2 X 10(-6)-2 X 10(-5) M), 5-hydroxytryptamine (MEC: 3 X 10(-6) M), GABA (MEC: 3 X 10(-4) M), L-homocysteic acid (MECs: 3 X 10(-5)-10(-4) M) and erythro-beta-hydroxy-L-glutamic acid (MEC: 3 X 10(-5) M). Acetylcholine showed varied effects, either excitatory or inhibitory, on the two neurons examined. No substances were found to have any marked excitatory effects on the neurons.