The bug-killer fly Gymnosoma rotundatum (L.) (Diptera: Tachinidae) forms the respiratory funnel independently of the host's immune response.

In internal parasitism, the respiration strategy within the host's body is as essential as evading attack from the host's immune system. Tachinid flies are parasitoids of terrestrial arthropods, mostly insects, during their larval stage. To obtain oxygen while living in the host body, they build a cylindrical structure known as the respiratory funnel at the aperture opened by the tachinid larva on the host integument or trachea. These funnels can be divided morphologically into sheath and cone types. Previous research on sheath-type funnels revealed that they are derived from the encapsulating substance produced by the host's immune system. In contrast, the cone-type funnels cover part of the body of the larval tachinid and may be constructed independently from the host immune system. To determine the mechanisms of cone-type funnel formation, histological observations were carried out on Gymnosoma rotundatum (L.) (Diptera: Tachinidae), which possesses this type of funnel. The respiratory funnel of G. rotundatum was found to be derived from the tube-shaped faeces wrapped with the peritrophic membrane and excreted by the fly larva, not from host tissue or haemocytes. Additionally, secretory glands putatively involved in the funnel formation were discovered around the larval anal plate of G. rotundatum. A comparison of funnel types within Tachinidae revealed that Phasiinae and Dexiinae have cone-type funnels, which may be created by the same mechanism as in G. rotundatum. These new findings suggest that funnel formation that does not use the host immune system is relevant to tachinid phylogeny.

A macroevolutionary role for chromosomal fusion and fission in Erebia butterflies.

The impact of large-scale chromosomal rearrangements, such as fusions and fissions, on speciation is a long-standing conundrum. We assessed whether bursts of change in chromosome numbers resulting from chromosomal fusion or fission are related to increased speciation rates in Erebia, one of the most species-rich and karyotypically variable butterfly groups. We established a genome-based phylogeny and used state-dependent birth-death models to infer trajectories of karyotype evolution. We demonstrated that rates of anagenetic chromosomal changes (i.e., along phylogenetic branches) exceed cladogenetic changes (i.e., at speciation events), but, when cladogenetic changes occur, they are mostly associated with chromosomal fissions rather than fusions. We found that the relative importance of fusion and fission differs among Erebia clades of different ages and that especially in younger, more karyotypically diverse clades, speciation is more frequently associated with cladogenetic chromosomal changes. Overall, our results imply that chromosomal fusions and fissions have contrasting macroevolutionary roles and that large-scale chromosomal rearrangements are associated with bursts of species diversification.

Thoracic crop formation is spatiotemporally coordinated with flight muscle histolysis during claustral colony foundation in Lasius japonicus queens.

In a majority of ants, a newly mated queen independently founds a colony and claustrally raises her first brood without foraging outside the nest. During claustral independent colony foundation (ICF) in several ants, the esophagus of the founding queen expands and develops into a "thoracic crop," which is then filled with a liquid substrate for larval feeding. It has been suggested that these substrates are converted from the founding queen's body reserves (e.g., histolyzed flight muscles) or redistributed from a gastral crop. Here, we describe thoracic crop development in Lasius japonicus queens during claustral ICF. The foundresses claustrally feed their larvae from weeks 2-5 after ICF onset, and the first worker emerges at week 6. The development proceeds as follows: in week 0, the foundress' dorsal esophageal wall is pleated and thickened. Then, from weeks 2-5, the esophagus expands toward a dorsal space previously occupied by flight muscles, following flight muscle histolysis. Gastral crop expansion follows esophageal expansion. Thus, thoracic crop formation may be spatiotemporally coordinated with flight muscle histolysis in Lasius japonicus queens, and similar developmental regulations might be common in other claustral ICF ants.

Forced expression of miR-143 and -145 in cardiomyocytes induces cardiomyopathy with a reductive redox shift.

BACKGROUND: Animal model studies show that reductive stress is involved in cardiomyopathy and myopathy, but the exact physiological relevance remains unknown. In addition, the microRNAs miR-143 and miR-145 have been shown to be upregulated in cardiac diseases, but the underlying mechanisms associated with these regulators have yet to be explored. METHODS: We developed transgenic mouse lines expressing exogenous miR-143 and miR-145 under the control of the alpha-myosin heavy chain (αMHC) promoter/enhancer. RESULTS: The two transgenic lines showed dilated cardiomyopathy-like characteristics and early lethality with markedly increased expression of miR-143. The expression of hexokinase 2 (HK2), a cardioprotective gene that is a target of miR-143, was strongly suppressed in the transgenic hearts, but the in vitro HK activity and adenosine triphosphate (ATP) content were comparable to those observed in wild-type mice. In addition, transgenic complementation of HK2 expression did not reduce mortality rates. Although HK2 is crucial for the pentose phosphate pathway (PPP) and glycolysis, the ratio of reduced glutathione (GSH) to oxidized glutathione (GSSG) was unexpectedly higher in the hearts of transgenic mice. The expression of gamma-glutamylcysteine synthetase heavy subunit (γ-GCSc) and the in vitro activity of glutathione reductase (GR) were also higher, suggesting that the recycling of GSH and its de novo biosynthesis were augmented in transgenic hearts. Furthermore, the expression levels of glucose-6-phosphate dehydrogenase (G6PD, a rate-limiting enzyme for the PPP) and p62/SQSTM1 (a potent inducer of glycolysis and glutathione production) were elevated, while p62/SQSTM1 was upregulated at the mRNA level rather than as a result of autophagy inhibition. Consistent with this observation, nuclear factor erythroid-2 related factor 2 (Nrf2), Jun N-terminal kinase (JNK) and inositol-requiring enzyme 1 alpha (IRE1α) were activated, all of which are known to induce p62/SQSTM1 expression. CONCLUSIONS: Overexpression of miR-143 and miR-145 leads to a unique dilated cardiomyopathy phenotype with a reductive redox shift despite marked downregulation of HK2 expression. Reductive stress may be involved in a wider range of cardiomyopathies than previously thought.

Genomic insights of body plan transitions from bilateral to pentameral symmetry in Echinoderms.

Echinoderms are an exceptional group of bilaterians that develop pentameral adult symmetry from a bilaterally symmetric larva. However, the genetic basis in evolution and development of this unique transformation remains to be clarified. Here we report newly sequenced genomes, developmental transcriptomes, and proteomes of diverse echinoderms including the green sea urchin (L. variegatus), a sea cucumber (A. japonicus), and with particular emphasis on a sister group of the earliest-diverged echinoderms, the feather star (A. japonica). We learned that the last common ancestor of echinoderms retained a well-organized Hox cluster reminiscent of the hemichordate, and had gene sets involved in endoskeleton development. Further, unlike in other animal groups, the most conserved developmental stages were not at the body plan establishing phase, and genes normally involved in bilaterality appear to function in pentameric axis development. These results enhance our understanding of the divergence of protostomes and deuterostomes almost 500 Mya.

Evolutionary transformation of mouthparts from particle-feeding to piercing carnivory in Viper copepods: Review and 3D analyses of a key innovation using advanced imaging techniques.

BACKGROUND: Novel feeding adaptations often facilitate adaptive radiation and diversification. But the evolutionary origins of such feeding adaptations can be puzzling if they require concordant change in multiple component parts. Pelagic, heterorhabdid copepods (Calanoida) exhibit diverse feeding behaviors that range from simple particle feeding to a highly specialized form of carnivory involving piercing mouthparts that likely inject venom. We review the evolutionary history of heterorhabdid copepods and add new high-resolution, 3D anatomical analyses of the muscular system, glands and gland openings associated with this remarkable evolutionary transformation. RESULTS: We examined four heterorhabdid copepods with different feeding modes: one primitive particle-feeder (Disseta palumbii), one derived and specialized carnivore (Heterorhabdus subspinifrons), and two intermediate taxa (Mesorhabdus gracilis and Heterostylites longicornis). We used two advanced, high-resolution microscopic techniques - serial block-face scanning electron microscopy and two-photon excitation microscopy - to visualize mouthpart form and internal anatomy at unprecedented nanometer resolution. Interactive 3D graphical visualizations allowed putative homologues of muscles and gland cells to be identified with confidence and traced across the evolutionary transformation from particle feeding to piercing carnivory. Notable changes included: a) addition of new gland cells, b) enlargement of some (venom producing?) glands, c) repositioning of gland openings associated with hollow piercing fangs on the mandibles, d) repurposing of some mandibular-muscle function to include gland-squeezing, and e) addition of new muscles that may aid venom injection exclusively in the most specialized piercing species. In addition, live video recording of all four species revealed mandibular blade movements coupled to cyclic contraction of some muscles connected to the esophagus. These behavioral and 3D morphological observations revealed a novel injection system in H. subspinifrons associated with piercing (envenomating?) carnivory. CONCLUSIONS: Collectively, these results suggest that subtle changes in mandibular tooth form, and muscle and gland form and location, facilitated the evolution of a novel, piercing mode of feeding that accelerated diversification of the genus Heterorhabdus. They also highlight the value of interactive 3D animations for understanding evolutionary transformations of complex, multicomponent morphological systems.

Pheromone gland development and monoterpenoid synthesis specific to oviparous females in the pea aphid.

BACKGROUND: Aphids display "cyclic parthenogenesis," in which parthenogenetically and sexually reproducing morphs seasonally alternate in the aphid annual life cycles. There are various characteristics that differ between asexual viviparous and sexual oviparous females. In oviparous females, swollen cuticular structures (~ 10 µm in diameter), called "scent plaques," are scattered on the surface of hind tibias, and secrete monoterpenoid sex pheromones. However, the developmental processes of the pheromone glands and the biosynthetic pathways of monoterpenoid pheromones have yet to be elucidated. RESULTS: Comparisons of the developmental processes that form hind tibias between sexual and parthenogenetic females revealed that, in sexual females, the epithelial tissues in proximal parts of hind tibias become columnar in fourth instar nymphs, and circular pheromone glands with Class 1 gland cells appear in adults, although they do not appear in parthenogenetic females. Furthermore, by comparing the expression levels of genes involved in the mevalonate pathway, which is required for monoterpenoid synthesis, we show that genes that encode the downstream enzymes in the pathway are highly expressed in hind tibias of sexual females. CONCLUSION: Glandular tissues of scent plaque are differentiated from the fourth instar in sexual females, while parthenogenetic females lack the glandular cells. Only the downstream steps of the mevalonate pathway appear to occur in scent plaques on hind tibias of sexual females, although the upstream steps may occur somewhere in other body parts.

Expansion of presoldier cuticle contributes to head elongation during soldier differentiation in termites.

In termites, the soldier caste possesses morphological features suitable for colony defence, despite some exceptions. Soldiers are differentiated via two moultings through a presoldier stage with dramatic morphogenesis. While a number of morphological modifications are known to occur during the presoldier moult, growth and morphogenesis seem to continue even after the moult. The present study, using the damp-wood termite Hodotermopsis sjostedti, carried out morphological and histological investigations on the developmental processes during the presoldier stage that is artificially induced by the application of a juvenile hormone analogue. Measurements of five body parameters indicated that head length significantly increased during the 14-day period after the presoldier moult, while it did not increase subsequently to the stationary moult (pseudergate moult as control). Histological observations also showed that the cuticular development played a role in the presoldier head elongation, suggesting that the soft and flexible presoldier cuticle contributed to the soldier morphogenesis in termites.

Aphid polyphenisms: trans-generational developmental regulation through viviparity.

Polyphenism, in which multiple discrete phenotypes develop from a single genotype, is considered to have contributed to the evolutionary success of aphids. Of the various polyphenisms observed in the complex life cycle of aphids, the reproductive and wing polyphenisms seen in most aphid species are conspicuous. In reproductive polyphenism, the reproductive modes can change between viviparous parthenogenesis and sexual reproduction in response to the photoperiod. Under short-day conditions in autumn, sexual morphs (males and oviparous females) are produced parthenogenetically. Winged polyphenism is observed in viviparous generations during summer, when winged or wingless (flightless) aphids are produced depending on a variety of environmental conditions (e.g., density, predators). Here, we review the physiological mechanisms underlying reproductive and wing polyphenism in aphids. In reproductive polyphenism, morph determination (male, oviparous or viviparous female) within mother aphids is regulated by juvenile hormone (JH) titers in the mothers. In wing polyphenism, although JH is considered to play an important role in phenotype determination (winged or wingless), the role is still controversial. In both cases, the acquisition of viviparity in Aphididae is considered to be the basis for maternal regulation of these polyphenisms, and through which environmental cues can be transferred to developing embryos through the physiological state of the mother. Although the mechanisms by which mothers alter the developmental programs of their progeny have not yet been clarified, continued developments in molecular biology will likely unravel these questions.

Two developmental switch points for the wing polymorphisms in the pea aphid Acyrthosiphon pisum.

BACKGROUND: In many insect taxa, wing polymorphism is known to be a consequence of tradeoffs between flight and other life-history traits. The pea aphid Acyrthosiphon pisum exhibits various morphs with or without wings associated with their complex life cycle including wing polyphenism in viviparous females, genetic wing polymorphism in males, and a monomorphic wingless phenotype in oviparous females and fundatrices. While wing differentiation has been investigated in some detail in viviparous females and males, these processes have not yet been elucidated in monomorphic morphs. The ontological development of the flight apparatus, including wings and flight muscles, was therefore carefully examined in oviparous females and fundatrices and compared with other morphs. RESULTS: The extensive histological examinations showed that flight-apparatus primordia were not at all produced throughout their postembryonic development in oviparous females and fundatrices, suggesting that during the embryonic stages the primordia are degenerated or not developed. In contrast, in viviparous females and males, the differentiation points to winged or wingless morphs occurred at the early postembryonic instars (first or second instar). CONCLUSIONS: Based on the above observations together with previous studies, we propose that there are two developmental switch points (embryonic and postembryonic) for the flight-apparatus development in A. pisum. Since there are multiple developmental trajectories for four wingless phenotypes (wingless viviparous females, oviparous females, fandatrices, wingless males), it is suggested that the developmental pathways leading to various morphs were evolutionarily acquired independently under selective pressures specific to each morph. Especially in viviparous females, the delay of determination is thought to contribute to the condition-dependent expressions of alternative phenotypes, that is, phenotypic plasticity.

Mutant γPKC that causes spinocerebellar ataxia type 14 upregulates Hsp70, which protects cells from the mutant's cytotoxicity.

Several missense mutations in the protein kinase Cγ (γPKC) gene have been found to cause spinocerebellar ataxia type 14 (SCA14), an autosomal dominant neurodegenerative disease. We previously demonstrated that the mutant γPKC found in SCA14 is misfolded, susceptible to aggregation and cytotoxic. Molecular chaperones assist the refolding and degradation of misfolded proteins and prevention of the proteins' aggregation. In the present study, we found that the expression of mutant γPKC-GFP increased the levels of heat-shock protein 70 (Hsp70) in SH-SY5Y cells. To elucidate the role of this elevation, we investigated the effect of siRNA-mediated knockdown of Hsp70 on the aggregation and cytotoxicity of mutant γPKC. Knockdown of Hsp70 exacerbated the aggregation and cytotoxicity of mutant γPKC-GFP by inhibiting this mutant's degradation. These findings suggest that mutant γPKC increases the level of Hsp70, which protects cells from the mutant's cytotoxicity by enhancing its degradation.

Congo red, an amyloid-inhibiting compound, alleviates various types of cellular dysfunction triggered by mutant protein kinase cγ that causes spinocerebellar ataxia type 14 (SCA14) by inhibiting oligomerization and aggregation.

Several missense mutations in the protein kinase Cγ (γPKC) gene have been found to cause spinocerebellar ataxia type 14 (SCA14), an autosomal dominant neurodegenerative disease. We previously demonstrated that the mutant γPKC found in SCA14 is susceptible to aggregation that induces apoptotic cell death. Congo red is widely used as a histological dye for amyloid detection. Recent evidence has revealed that Congo red has the property to inhibit amyloid oligomers and fibril formation of misfolded proteins. In the present study, we examine whether Congo red inhibits aggregate formation and cytotoxicity of mutant γPKC. Congo red likely inhibits aggregate formation of mutant γPKC ­ green fluorescent protein (GFP) without affecting its expression level in SH-SY5Y cells. Congo red counteracts the insolubilization of recombinant mutant γPKC, suggesting that the dye inhibits aggregation of mutant γPKC by a direct mechanism. Congo red also inhibits aggregation and oligomerization of mutant γPKC-GFP in primary cultured cerebellar Purkinje cells. Moreover, the dye reverses the improper development of dendrites and inhibits apoptotic cell death in Purkinje cells that express mutant γPKC-GFP. These results indicate that amyloid-inhibiting compounds like Congo red may be novel therapeutics for SCA14.