Conservation genetics of harvested river turtles, Podocnemis expansa and Podocnemis unifilis, in the Peruvian Amazon: all roads lead to Iquitos

We present a mtDNA analysis of Podocnemis expansa (n = 81) and Podocnemis unifilis (n = 228) turtles traded in Peru to evaluate the potential origin of these animals. In particular, we were interested in the relationship between samples reported in the Iquitos markets (IMs) and a Pacaya Samiria Natural Reserve (PSNR) where illegal hunting is presumed. Our mtDNA data showed that, for both species, all haplotypes found within the PSNR were observed in the IM, and that these markets also displayed haplotypes not documented in the reserve. This suggests that the IMs are recipients of Podocnemis turtles from within and outside the PSNR. The fact that most of the haplotype diversity observed in the markets was not found within the PSNR strongly suggests that Podocnemis genetic diversity is exploited in areas where conservation actions are limited. Hence, we recommend expanding Podocnemis conservation efforts outside of protected areas.     

Mouth dimorphism in scale‐eating cichlid fish from Lake Tanganyika advances individual fitness

Random asymmetry, that is the coexistence of left‐ and right‐sided (or ‐handed) individuals within a population, is a particular case of natural variation; what triggers and maintains such dimorphisms remains unknown in most cases. Here, we report a field‐based cage experiment in the scale‐eating Tanganyikan cichlid Perissodus microlepis, which occurs in two morphs in nature: left‐skewed and right‐skewed individuals with respect to mouth orientation. Using underwater cages stocked with scale‐eaters and natural prey fish, we first confirm that, under semi‐natural conditions, left‐skewed scale‐eaters preferentially attack the right flank of their prey, whereas right‐skewed individuals feed predominantly from the left side. We then demonstrate that scale‐eaters have a higher probability for successful attacks when kept in dimorphic experimental populations (left‐ and right‐skewed morphs together) as compared to monomorphic populations (left‐ or right‐skewed morphs), most likely because prey fishes fail to accustom to strikes from both sides. The significantly increased probability for attacks appears to be the selective agent responsible for the evolution and maintenance of mouth dimorphism in P. microlepis, lending further support to the hypothesis that negative frequency‐dependent selection is the stabilizing force balancing the mouth dimorphism at quasi‐equal ratios in scale‐eating cichlids.     

A glyceraldehyde-3-phosphate dehydrogenase with eubacterial features in the amitochondriate eukaryote,Trichomonas vaginalis

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH), localized in the cytosol of Trichomonas vaginalis, was partially purified. The enzyme is specific for NAD⁺ and is similar in most of its catalytic properties to glycolytic GAPDHs from other organisms. Its sensitivity to koningic acid is similar to levels observed in GAPDHs from eubacteria and two orders of magnitude lower than those observed for eukaryotic GAPDHs. The complete amino acid sequence of T. vaginalis GAPDH was derived from the N-terminal sequence of the purified protein and the deduced sequence of a cDNA clone. It showed great similarity to other eubacterial and eukaryotic GAPDH sequences. The sequence of the S-loop displayed a eubacterial signature. The overall sequence was more similar to eubacterial sequences than to cytosolic and glycosomal eukaryotic sequences. In phylogenetic trees obtained with distance matrix and parsimony methods T. vaginalis GAPDH clustered with its eubacterial homologs. GAPDHs of other amitochondriate protists, belonging to early branches of the eukaryotic lineage (Giardia lamblia and Entamoeba histolytica—Smith M.W. and Doolittle R.F., unpublished data in GenBank), showed typical eukaryotic signatures and clustered with other eukaryotic sequences, indicating that T. vaginalis GAPDH occupies an anomalous position, possibly due to horizontal gene transfer from a eubacterium. Correspondence to: M. Müller     

Aversive Learning in the Praying Mantis (<Emphasis Type="Italic">Tenodera aridifolia</Emphasis>), a Sit and Wait Predator

Animals learn to associate sensory cues with the palatability of food in order to avoid bitterness in food (a common sign of toxicity). Associations are important for active foraging predators to avoid unpalatable prey and to invest energy in searching for palatable prey only. However, it has been suggested that sit-and-wait predators might rely on the opportunity that palatable prey approach them by chance: the most efficient strategy could be to catch every available prey and then decide whether to ingest them or not. In the present study, we investigated avoidance learning in a sit-and-wait predator, the praying mantis (Tenodera aridifolia). To examine the effects of conspicuousness and novelty of prey on avoidance learning, we used three different prey species: mealworms (novel prey), honeybees (novel prey with conspicuous signals) and crickets (familiar prey). We sequentially presented the prey species in pairs and made one of them artificially bitter. In the absence of bitterness, the mantises consumed bees and crickets more frequently than mealworms. When the prey were made bitter, the mantises still continued to attack bitter crickets as expected. However, they reduced their attacks on bitter mealworms more than on bitter bees. This contrasts with the fact that conspicuous signals (e.g. coloration in bees) facilitate avoidance learning in active foraging predators. Surprisingly, we found that the bitter bees were totally rejected after an attack whereas bitter mealworms were partially eaten (~35%). Our results highlight the fact that the mantises might maintain a selection pressure on bees, and perhaps on aposematic species in general.     

Soluble Epoxide Hydrolase Inhibition Attenuates MPTP-Induced Neurotoxicity in the Nigrostriatal Dopaminergic System: Involvement of α-Synuclein Aggregation and ER Stress

Soluble epoxide hydrolase (sEH) is widely expressed in the mammalian brain and possesses dual enzymatic activities, including C-terminal epoxide hydrolase (C-EH) which degrades epoxyeicosatrienoic acid (EET), a beneficial arachidonic acid metabolite. In the present study, the neuroprotective effect of sEH inhibition on 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced neurodegeneration of nigrostriatal dopaminergic system was investigated using genetic and pharmacological approaches. MPTP (15 mg/kg) was intraperitoneally injected in sEH knockout (KO) mice and C57BL/6J mice as wild-type (WT) mice. Compared with the MPTP-treated WT mice, MPTP-induced reductions in striatal dopamine content and nigral tyrosine hydroxylase level (TH, a biomarker of dopaminergic neurons) were less significant in the treated sEH mice. Furthermore, MPTP-induced HO-1 elevation (a redox-regulated protein), α-synuclein aggregation, and caspase 12 activation (a hallmark of ER stress) were less prominent in sEH KO mice than in WT mice. These data indicate that sEH KO mice are more resistant to MPTP-induced neurotoxicity. The pharmacological effect of N-[1-(1-oxopropyl)-4-piperidinyl]-N0-[4-(trifluoromethoxy)phenyl)-urea (TPPU, an sEH inhibitor) on MPTP-induced neurotoxicity was investigated in WT mice. TPPU (1 mg/kg, i.p.) attenuated MPTP-induced reduction in striatal dopamine content, TH-positive cell numbers, TH, and pro-caspase 9 protein levels (an initiator caspase of apoptosis) in mouse SN. Moreover, TPPU reduced MPTP-induced HO-1 elevation, α-synuclein aggregation and caspase 12 activation, indicating that TPPU is effective in attenuating MPTP-induced oxidative stress, apoptosis, protein aggregation, and ER stress. In conclusion, our study suggests that sEH is a potential target for developing therapies for parkinsonism. Furthermore, sEH inhibitors may be of clinical significance for treating CNS neurodegenerative diseases.     

Ecology of the variegated grasshopper, Zonocerus variegatus, (Orthoptera: Acridoidea, Pyrgomorphidae) on the Nsukka Plateau, Nigeria

A study of the local population of the variegated grasshopper, Z. variegatus on the Nsukka Plateau, Nigeria, has shown that there are two populations, the dry season and the wet season populations, whose life-histories overlap.The average span of life, from nymph to adult of the individuals of either population is 9–10 months, while development from nymph to reproductive maturity in either form is 4–5 months. For the dry season population, nymphs appear in October, young adults by March–April, and by August the last remnants of this population die out. The wet season individuals appear first as nymphs by about February, as young adults by June, and die out by about December. In general, egg pods remain in the soil for 5–6 months (April–October), and for 4–5 months (October–February) for the dry season and wet season individuals respectively, before hatching. The shorter period spent in the soil by the eggs of the wet season individuals appears to be due to the fact of delay of oviposition in the mature females by the extreme wetness of the soil when reproductive maturity is attained.In the laboratory, attempts to mate reproductively mature and copulating adults from either seasonal population with each other, were not successful.The phenology of the dry season population is the same, whether reared in the laboratory or in the field.The growth characteristics of these grasshoppers conform to Dyar's rule. However, while growth as indicated by increases in mean body length is linear, growth as indicated by weight measurements shows a two-phase relationship, the divergence appearing at the IV instar.

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Résumé Une étude de la population locale de Z. variegatus sur le Plateau Nsukka au Nigeria, a montré qu'il y a en fait coexistence de deux populations distinctes, dont les cycles biologiques se chevauchent, l'une correspondant à la saison sèche et l'autre à la saison humide.La longévité moyenne des individus (vie larvaire + vie imaginale) dans l'une ou l'autre de ces populations est de 9 à 10 mois, le développement, depuis la larve jusqu'à la maturité sexuelle, étant de 4 à 5 mois. Pour la population de la saison sèche, les larves apparaissent en octobre, les jeunes adultes en mars–avril, et les derniers survivants s'observent jusqu'en août. Les larves des individus de la saison humide apparaissent courant février, leurs jeunes adultes en juin, et la population s'éteint en décembre.En général les coques ovigères n'éclosent qu'après un séjour dans le sol de 5 à 6 mois (avril à octobre) pour la population de la saison sèche, et de 4 à 5 mois (octobre à février) pour la population de la saison humide. Le fait que le temps d'incubations dans le sol soit plus court pour les ufs déposés par les individus de la saison humide serait dû à ce que, lorsque ces femelles auront atteint leur maturité, l'extrême humidité du sol ne permettra pas la ponte qui se trouvera ainsi retardée.Les tentatives faites en laboratoire, pour croiser entre eux des adultes génitalement mûrs provenant de chacune de ces 2 populations, ont échoué.La phénologie de la population de la saison sèche reste la même, que celle-ci soit élevée au laboratoire ou dans la nature.Les caractéristiques de la croissance de ces Orthoptères sont conformes à la règle de Dyar. Toutefois, tandis que cette croissance est linéaire quand on la mesure d'après la longueur du corps, on y relève deux phases si l'on se réfère au poids des individus, la divergence se manifestant à partir du 4 e stade larvaire.

     

Variation of anal fin egg‐spots along an environmental gradient in a haplochromine cichlid fish

Male secondary sexual traits are targets of inter‐ and/or intrasexual selection, but can vary due to a correlation with life‐history traits or as by‐product of adaptation to distinct environments. Trade‐offs contributing to this variation may comprise conspicuousness toward conspecifics versus inconspicuousness toward predators, or between allocating resources into coloration versus the immune system. Here, we examine variation in expression of a carotenoid‐based visual signal, anal‐fin egg‐spots, along a replicate environmental gradient in the haplochromine cichlid fish Astatotilapia burtoni. We quantified egg‐spot number, area, and coloration; applied visual models to estimate the trait's conspicuousness when perceived against the surrounding tissue under natural conditions; and used the lymphocyte ratio as a measure for immune activity. We find that (1) males possess larger and more conspicuous egg‐spots than females, which is likely explained by their function in sexual selection; (2) riverine fish generally feature fewer but larger and/or more intensely colored egg‐spots, which is probably to maintain signal efficiency in intraspecific interactions in long wavelength shifted riverine light conditions; and (3) egg‐spot number and relative area correlate with immune defense, suggesting a trade‐off in the allocation of carotenoids. Taken together, haplochromine egg‐spots feature the potential to adapt to the respective underwater light environment, and are traded off with investment into the immune system.