Ontogeny of the jaw and maxillary barbel musculature in the armoured catfish families Loricariidae and Callichthyidae (Loricarioidea,Siluriformes), with a discussion on muscle homologies

The neotropical loricarioid catfishes include six families, the most species‐rich of which are the Callichthyidae and the Loricariidae. Loricariidae (suckermouth armoured catfishes) have a highly specialized head morphology, including an exceptionally large number of muscles derived from the adductor mandibulae complex and the adductor arcus palatini. Terminology of these muscles varies among the literature, and no data exist on their ontogenetic origin. A detailed examination of the ontogeny of both a callichthyid and a loricariid representative now reveals the identity of the jaw and maxillary barbel musculature, and supports new hypotheses concerning homologies. The adductor mandibulae muscle itself is homologous to the A1‐OST and A3′ of basal catfishes, and the A3′ has given rise to the newly evolved loricariid retractor veli as well. The A2 and A3″ have resulted in the retractor tentaculi of Callichthyidae and the retractor premaxillae of Loricariidae. Thus, these two muscles are shown to be homologous. In Loricariidae, the extensor tentaculi consists of two separate muscles inserting on the autopalatine, and evidence is given on the evolutionary origin of the loricariid levator tentaculi (previously and erroneously known as retractor tentaculi) from the extensor tentaculi, and not the adductor mandibulae complex. © 2009 The Linnean Society of London, Zoological Journal of the Linnean Society, 2009, 155 , 76–96.     

Estimation of the forces generated by the thigh muscles for transtibial amputee gait

The forces generated by the muscles with origin on the human femur play a major role in transtibial amputee gait, as they are the most effective of the means that the body can use for propulsion. By estimating the forces generated by the thigh muscles of transtibial amputees, and comparing them to the forces generated by the thigh muscles of normal subjects, it is possible to better estimate the energy output needed from prosthetic devices. The purpose of this paper is to obtain the forces generated by the thigh muscles of transtibial amputees and compare these with forces obtained from the same muscles in the case of normal subjects. Two transtibial amputees and four normal subjects similar in size to the amputees were investigated. Level ground walking was chosen as the movement to be studied, since it is a common activity that most amputees engage in. Inverse dynamics and a muscle recruitment algorithm (developed by AnyBody Technology^®) were used for generating the muscle activation patterns and for computing the muscle forces. The muscle forces were estimated as two sums: one for all posterior muscles and one for the anterior muscles, based on the position of the muscles of the thigh relative to the frontal plane of the human body. The results showed that a significantly higher force is generated by the posterior muscles of the amputees during walking, leading to a general increase of the metabolic cost necessary for one step.     

Phylogeny of Palaearctic Syrphidae (Diptera): evidence from larval stages

We estimated the phylogeny of Palaearctic Syrphidae using 187 larval morphological characters obtained from about 65% of the fauna (85 supraspecific taxa represented by 118 species) and based the analysis at the generic, level. The root of the syrphid tree was established from an outgroup consisting of other Aschizan families: the Platypezidae, Phoridae and Pipunculidae, with the tree rooted on the Lonchopteridae. The Syrphidae was the most derived Aschizan family. The Pipunculidae was the sister group to the Syrphidae. Eumerus was basal within Syrphidae. A trend exists towards increasing complexity of integumental folds and grooves across the Aschiza. In movement, the integument collapses along the line of these grooves. Grooves are evidence of muscles forming functional groups. Elaboration of independent groups of muscles appears to underlie much of the evolution of larval form within Aschiza. The basal feeding modes of syrphid larvae are mycophagy and phytophagy. Above these feeding modes, all remaining syiphids fall into one of two lineages comprising entomophages and saprophages, each of which has a single origin within the apparently polyphyletic Volucella. Major morphological innovation is associated with shifts between feeding modes; within feeding modes, change is gradual and tends towards increasing complexity. Change is mostly in structures associated with the mouthparts, thorax, anal segment and locomotory organs. Generic diagnoses with biological and taxonomic notes and a key to genera using larval characters are provided.     

A muscle-path-plane method for representing muscle contraction during joint movement

Traditional muscle paths (the straight-line model and the viapoint-line model) emphasise either the mechanical properties that arouse joint movement or the morphological characteristics of the muscles. To consider both the factors, a muscle-path-plane (MPP) method is introduced to model the paths of muscles during joint movement. This method is based on the premise that there is a MPP, constructed by origin, insertion and MPP control point, which represents the major direction of the muscle contraction for an arbitrary joint configuration at any time. Then, we can calculate the functions and the lengths of the muscle paths during instantaneous joint movement in MPP by mathematical approaches. Taking the triceps brachii as an example, the lengths of its paths during elbow flexion are calculated and compared with the relative studies reported in the literature. It is concluded that this method can provide an insight into the simulation of the muscle contraction.     

Microanatomy of adult zebrafish extraocular muscles

Binocular vision requires intricate control of eye movement to align overlapping visual fields for fusion in the visual cortex, and each eye is controlled by 6 extraocular muscles (EOMs). Disorders of EOMs are an important cause of symptomatic vision loss. Importantly, EOMs represent specialized skeletal muscles with distinct gene expression profile and susceptibility to neuromuscular disorders. We aim to investigate and describe the anatomy of adult zebrafish extraocular muscles (EOMs) to enable comparison with human EOM anatomy and facilitate the use of zebrafish as a model for EOM research. Using differential interference contrast (DIC), epifluorescence microscopy, and precise sectioning techniques, we evaluate the anatomy of zebrafish EOM origin, muscle course, and insertion on the eye. Immunofluorescence is used to identify components of tendons, basement membrane and neuromuscular junctions (NMJs), and to analyze myofiber characteristics. We find that adult zebrafish EOM insertions on the globe parallel the organization of human EOMs, including the close proximity of specific EOM insertions to one another. However, analysis of EOM origins reveals important differences between human and zebrafish, such as the common rostral origin of both oblique muscles and the caudal origin of the lateral rectus muscles. Thrombospondin 4 marks the EOM tendons in regions that are highly innervated, and laminin marks the basement membrane, enabling evaluation of myofiber size and distribution. The NMJs appear to include both en plaque and en grappe synapses, while NMJ density is much higher in EOMs than in somatic muscles. In conclusion, zebrafish and human EOM anatomy are generally homologous, supporting the use of zebrafish for studying EOM biology. However, anatomic differences exist, revealing divergent evolutionary pressures.     

Molecular phylogeny of araneomorph spiders

The reconstruction of the phylogeny of spiders based on morphological and ethological characters is hampered by frequent homoplasies. Therefore, fragments of the 28S rRNA gene have been sequenced to elucidate some crucial points in the evolution of spiders. The following results were obtained. (1) The 28S rRNA gene data support the monophyly of the Entelegynae. Thus, the number of different subunits and the number of hexamers which form a haemocyanin complex must have been reduced at least twice within the spiders. The character state pattern within the spiders and within the Arachnida suggests that these reductions are due to a decrease in the selection on the oxygen binding properties of the haemocyanins as a result of the evolution of tracheae. (2) The semientelegyne spiders are not a transition stage between the Haplogynae and the Entelegynae. The lack of separate fertilization ducts in these species is probably due to secondary reduction. This reduction has decisive consequences for the flow of the sperm and for sperm competition. (3) Furthermore, the 28S rRNA gene data tentatively support the hypothesis that the orb web is either a plesiomorphy or has evolved at least twice.     

Trends in the Actions of Mammalian Masticatory Muscles

The actions of the masticatory muscles of a variety of mammalsin which feeding behavior and the configuration of the masticatoryapparatus differ have been reported. The most common approachused in these studies involves (1) obtaining a good anatomicalperception of the musculature, (2) deriving a theoretical modelof the actions of these muscles during jaw movement, and (3)testing this model by recording muscle activity and jaw movementssimultaneously. A catalogue of the activity patterns in eleven species of mammalsduring food reduction reveals certain trends in the actionsof the masticatory muscles. Horizontal jaw movements are generatedprimarily by differential activities of the deep temporalis,superficial masseter, and medial pterygoid. Vertical movementsand the maintenance of tooth to food contact apparently areproduced by action of the superficial temporalis, deep masseter,and zygomaticomandibularis. Thus, horizontal movements are seeminglygenerated by muscles having fibers arranged in marked anteroposteriordirection, whereas vertical movements are generated by muscleshaving more or less vertically arranged fibers. The asymmetry of jaw movement and the muscular activity generatingit suggest that mastication involves an interactionbetween anunbalanced and flexible functional unit (muscles) and a balancedand stable structural unit (skull and teeth). Thus, any unbalancingof the structural unit results in a further unbalancing of themasticatory process.     

The phylogenetic placement of Psechridae within Entelegynae and the convergent origin of orb‐like spider webs

Evolutionary convergence of phenotypic traits provides evidence for their functional success. The origin of the orb web was a critical event in the diversification of spiders that facilitated a spectacular radiation of approximately 12 000 species and promoted the evolution of novel web types. How the orb web evolved from ancestral web types, and how many times orb‐like architectures evolved in spiders, has been debated for a long time. The little known spider genus Fecenia (Psechridae) constructs a web that resembles the archetypical orb web, but morphological data suggest that Psechridae (Psechrus + Fecenia) does not belong in Orbiculariae, the ‘true orb weavers’, but to the ‘retrolateral tibial apophysis (RTA) clade’ consisting mostly of wandering spiders, but also including spiders building less regular webs. Yet, the data are sparse and no molecular phylogenetic study has estimated Fecenia's exact position in the tree of life. Adding new data to sequences pulled from GenBank, we reconstruct a phylogeny of Entelegynae and phylogenetically test the monophyly and placement of Psechridae, and in doing so, the alternative hypotheses of monophyletic origin of the orb web and the pseudo‐orb versus their independent origins, a potentially spectacular case of behavioural convergence. We also discuss the implications of our results for Entelegynae systematics. Our results firmly place a monophyletic Psechridae within the RTA clade, phylogenetically distant from true orb weavers. The architectural similarities of the orb and the pseudo‐orb are therefore clearly convergent, as also suggested by detailed comparisons of these two web types, as well as the spiders' web‐building behaviours and ontogenetic development. The convergence of Fecenia webs with true orbs provides a remarkable opportunity to investigate how these complex sets of traits may have interacted during the evolution of the orb.     

从16S rRNA基因序列初步探讨拟壁钱属和壁钱属蜘蛛系统发生关系

拟壁钱属Oecobius和壁钱属Uroctea蜘蛛之间系统发生关系存在一定的争议.为从分子水平探讨两属间系统发生关系,本研究测定了5科6种蜘蛛的16S rRNA基因部分序列,并联合来自GenBank的8科8种蜘蛛16S rRNA基因序列数据重建分子系统树.结果表明,拟壁钱属和壁钱属间遗传距离(28.1%)明显大于复杂生殖器类(Entelegynae)蜘蛛属间遗传距离的平均值(22.9%);与目前大多数文献把拟壁钱属和壁钱属并在一个科的观点相反,本研究重建的系统发生树显示两属不是姊妹群.作者建议把拟壁钱属和壁钱属分别重新划回拟壁钱科Oecobiidae和壁钱科Urocteidae.系统发生树还验证了简单生殖器类(Haplogynae)蜘蛛、复杂生殖器类蜘蛛各自的单系性以及筛器类(Cribellate)蜘蛛的多系发生,同时本文的结果还对圆网蛛类(Orbiclariae)单系发生及RTA类群单系发生的有效性提出了质疑.     

Mechanical advantage of area of origin for the external pterygoid muscle in two murid rodents, Apodemus speciosus and Clethrionomys rufocanus

The actions of masticatory muscles in relation to transverse grinding, associated with forward masticatory movement of the mandible, were investigated by using a mechanical model in the two murid rodents, the Japanese field mouse (Apodemus speciosus: subfamily Murinae) and the gray red-backed vole (Clethrionomys rufocanus: subfamily Arvicolinae). Furthermore, statics of the masticatory system on a sagittal plane while chewing is taking place were also analyzed in these rodents. The inward grinding movements of hemimandibles are generated by the posterior temporalis and internal and external pterygoids in both species. In addition to these muscles, the anterior temporalis also moves the hemimandibles lingually in Apodemus speciosus. The area of origin of the external pterygoid seems more advantageous for transverse grinding in A. speciosus than in Clethrionomys rufocanus. On the basis of the static analysis, the anterodorsal area of origin of the external pterygoid to the upper second and third molars in Clethrionomys rufocanus appears to be an adaptive character to prevent the jaw joints from dislocation during occlusion at a posterior point on the elongated row of cheek teeth.     

PRRT2 mutations cause benign familial infantile epilepsy and infantile convulsions with choreoathetosis syndrome

Benign familial infantile epilepsy (BFIE) is a self-limited seizure disorder that occurs in infancy and has autosomal-dominant inheritance. We have identified heterozygous mutations in PRRT2, which encodes proline-rich transmembrane protein 2, in 14 of 17 families (82%) affected by BFIE, indicating that PRRT2 mutations are the most frequent cause of this disorder. We also report PRRT2 mutations in five of six (83%) families affected by infantile convulsions and choreoathetosis (ICCA) syndrome, a familial syndrome in which infantile seizures and an adolescent-onset movement disorder, paroxysmal kinesigenic choreoathetosis (PKC), co-occur. These findings show that mutations in PRRT2 cause both epilepsy and a movement disorder. Furthermore, PRRT2 mutations elicit pleiotropy in terms of both age of expression (infancy versus later childhood) and anatomical substrate (cortex versus basal ganglia).     

Phenotypic variability at the TGF-β1 locus in Camurati-Engelmann disease

Camurati-Engelmann disease (CED) [OMIM 131300] is an autosomal dominant sclerosing bone dysplasia recently ascribed to mutations of the transforming growth factor (TGF-beta1) gene on chromosome 19q13.1-q13.3. Five mutations consistently located in the TGF-beta1 propeptide have been hitherto identified in 21 families. Here, we report on TGF-beta1 mutations in one Australian and six European families. Three distinct mutations were identified among seven families: namely, R218H (family 1), R218C (families 2, 6, 7) and C225R (families 3, 4, 5). The three mutations identified in our pedigrees have been previously observed in families of Japanese and Israeli origin and the R218C appears to be the most prevalent mutation worldwide (17/28 reported families). No obvious correlation between the nature of the mutations and the severity of the clinical manifestations could be established, but a marked intrafamilial clinical variability was observed, supporting incomplete penetrance of CED. Interestingly, the polymorphisms in the TGF-beta1 gene showed no correlation with the severity of the disease. We conclude that CED is a clinically variable condition and that this clinical variability is not accounted for by polymorphisms at the TGF-beta1 locus.     

Family origin and the response of threespine stickleback, Gasterosteus aculeatus, to thermal acclimation

To establish whether family origin affects the response of the threespine stickleback (Gasterosteus aculeatus) to thermal acclimation, we examined the rates of feeding, growth, and food conversion, relative tissue and organ masses and activities of a mitochondrial and a glycolytic enzyme in pectoral and axial muscle of individually housed fish from six families during acclimation to 8 degrees C and 23 degrees C. Feeding rates differed among families but were consistently higher in warm-acclimated than cold-acclimated fish. Growth rates differed among families. In four families growth was greater at 8 degrees C; these families generally had higher conversion efficiencies at 8 degrees C than 23 degrees C. For two families, growth was greater at 23 degrees C than 8 degrees C and conversion efficiencies did not differ between 8 degrees C and 23 degrees C. Relative tissue and organ masses (percent axial muscle, hepatosomatic, gut and kidney indices) differed with gender and among families (hepatosomatic, gut and kidney indices) but little with acclimation status. In all families and in both muscles, activities of the mitochondrial enzyme, citrate synthase (CS), were increased by cold acclimation. Axial muscle levels of the glycolytic enzyme, lactate dehydrogenase (LDH), were not affected by thermal acclimation or family origin, but were strongly correlated with the hepatosomatic index and axial muscle protein content. Pectoral muscle levels of LDH were affected by family origin which also influenced the response to thermal acclimation. Similar patterns were observed for specific activities and total muscle contents of these enzymes. Stickleback family origin influenced rates of feeding and growth and the thermal sensitivity of growth rates but not the compensatory increase in muscle CS levels with cold acclimation. The differing thermal sensitivities of growth could reflect distinct strategies for the timing of juvenile growth.     

The ontogenetical and supposed phylogenetical fate of the parietal muscles in the Ctenostomata (Bryozoa)

A new term, “trophon”, has been introduced for the feeding and sexually propagating unit in the stolonate ctenostomes; the “stolon” and the “trophon” represent “sukzooids”, because they are homologous only to parts of the autozooids in the uniserially arranged ctenostomes. – The ontogeny of the muscles, especially the parietal muscles, has been studied in 17 species of ctenostomatous bryozoans belonging to different sub-groups of this order; the main effort was directed toward the details of the differentiations in living animals (14 of the investigated species). In various species of the Ctenostomata two separate sets of parietal muscles develop – probably as a consequence of the elongation of the cystid; the functional parietal muscles in the trophons of the stolonial forms are homologous to the secondary parietal muscles found in several uniserial ctenostomes. Contrary to the supposition by Soule (1954) in the different families of the serially arranged forms the muscles appear in different sequences during the development of the zooid and partly have different ontogenetical fates. Neither the “Carnosa” nor the “Paludicellea” (s. 1.) nor the “Stolonifera” can be maintained as taxa with the argument of a similar ontogeny of the muscles. A detailed comparison regarding the fate of the parietal muscles (and the polypide anlage) showed similarities between certain of the uniserial to either some of the stolonial, the sheet like, or the cystid-fusing forms suggesting a separate evolutionary origin of the advanced forms in those groups of the serially growing forms. – A new family, Pottsiellidae fam. nov., has been introduced and defined.     

Presence of anisotropic (birefringent) crystalline structures in embryonic and juvenile monogonont rotifers

A systematic survey for the presence of birefringent (anisotropic) structures in rotifers was undertaken. Several common features of rotifers exhibit anisotropism (e.g. trophi & muscles). However, unusual anisotropic crystalline structures (ACS) were found in late stage embryos (i.e. possessing eyespots and trophi, and showing movement). ACS were found in 18 of 26 species of monogonont rotifers (comprising 11 genera of 5 families). In Sinantherina socialis, ACS were present in the lower gut as compact, spherical masses of minute crystals that slowly broke apart and disappeared within 20 hours of hatching. Although several authors have described the existence of refractive bodies in rotifers, to my knowledge this is the first report of their birefringent properties.     

A dual fate of the hindlimb muscle mass: cloacal/perineal musculature develops from leg muscle cells

The cloaca serves as a common opening to the urinary and digestive systems. In most mammals, the cloaca is present only during embryogenesis, after which it undergoes a series of septation events leading to the formation of the anal canal and parts of the urogenital tract. During embryogenesis it is surrounded by skeletal muscle. The origin and the mechanisms regulating the development of these muscles have never been determined. Here, we show that the cloacal muscles of the chick originate from somites 30-34, which overlap the domain that gives rise to leg muscles (somites 26-33). Using molecular and cell labelling protocols, we have determined the aetiology of cloacal muscles. Surprisingly, we found that chick cloacal myoblasts first migrate into the developing leg bud and then extend out of the ventral muscle mass towards the cloacal tubercle. The development of homologous cloacal/perineal muscles was also examined in the mouse. Concordant with the results in birds, we found that perineal muscles in mammals also develop from the ventral muscle mass of the hindlimb. We provide genetic evidence that the perineal muscles are migratory, like limb muscles, by showing that they are absent in metd/d mutants. Using experimental embryological procedures (in chick) and genetic models (in chick and mouse), we show that the development of the cloacal musculature is dependent on proximal leg field formation. Thus, we have discovered a novel developmental mechanism in vertebrates whereby muscle cells first migrate from axially located somites to the pelvic limb, then extend towards the midline and only then differentiate into the single cloacal/perineal muscles.     

Possible contributions of CPG activity to the control of rhythmic human arm movement

There is extensive modulation of cutaneous and H-reflexes during rhythmic leg movement in humans. Mechanisms controlling reflex modulation (e.g., phase- and task-dependent modulation, and reflex reversal) during leg movements have been ascribed to the activity of spinal central pattern generating (CPG) networks and peripheral feedback. Our working hypothesis has been that neural mechanisms (i.e., CPGs) controlling rhythmic movement are conserved between the human lumbar and cervical spinal cord. Thus reflex modulation during rhythmic arm movement should be similar to that for rhythmic leg movement. This hypothesis has been tested by studying the regulation of reflexes in arm muscles during rhythmic arm cycling and treadmill walking. This paper reviews recent studies that have revealed that reflexes in arm muscles show modulation within the movement cycle (e.g., phase-dependency and reflex reversal) and between static and rhythmic motor tasks (e.g., task-dependency). It is concluded that reflexes are modulated similarly during rhythmic movement of the upper and lower limbs, suggesting similar motor control mechanisms. One notable exception to this pattern is a failure of contralateral arm movement to modulate reflex amplitude, which contrasts directly with observations from the leg. Overall, the data support the hypothesis that CPG activity contributes to the neural control of rhythmic arm movement.     

Head morphology of selected Staphylinoidea (Coleoptera: Staphyliniformia) with an evaluation of possible groundplan features in Staphylinidae

In insects, anatomical features of the head have been found to provide important information for phylogenetic and comparative evolutionary studies. We analyzed the internal head morphology of three (omaliine, tachyporine, oxyteline group) out of the four subfamily groups of the beetle family Staphylinidae plus two non‐staphylinid outgroups (i.e., Agyrtidae and Leiodidae). Synchrotron X‐ray micro‐tomography was used to obtain comparative head anatomical datasets of eight species to describe (i) the presence/absence of muscles inside the head capsule and (ii) the variability in their points of origin. Nineteen of these muscles were phylogenetically informative (nine with respect to presence/absence and eleven with respect to the origin; one muscle had an influence on both analyses) and were used in character mapping analyses to reconstruct groundplan patterns of the head musculature in Staphylinidae and their subgroups. Three muscles (Mm. 7, 9, 50) were identified as possibly autapomorphic for Staphyliniformia. The taxon (Agyrtidae + Leiodidae) is supported by the absence of M. 9. The monophyly of the tachyporine group is supported by a common origin of M. 4. Aleocharinae, a subfamily within the tachyporine group, is supported by the absence of M. 42 and possibly by numerous points of origin of various muscles (Mm. 1, 17, 28, 29, 30). Our analysis of the general organization of the hypopharynx‐prementum‐complex has revealed that this complex is organized in a similar way in the investigated staphylinoids, i.e., with the prementum lying anteriorly to and being in line with the hypopharynx and the mentum. We have found deviating conditions in the investigated species of the Aleocharinae, in which the prementum can be largely retracted posteriorly. Consequently, it is sandwiched between the ventral mentum and the dorsal hypopharyngeal region. The hypopharyngeal region is thus lifted dorsad to a large extent, approaching the cibarial roof. This situation is paralleled by a loss of the hypopharyngeal retractor (M. 42) and a shift of origin of premental retractors (Mm. 28–30) posteriorly toward the gula. J. Morphol. 270:1503–1523, 2009. © 2009 Wiley‐Liss, Inc.     

The alien flora of Europe: a taxonomic and biogeographic review

Abstract. A geographic and taxonomic overview of the non-indigenous plant species of Europe, based on the ‘Flora Europaea’ is given. The flora of Europe includes 1568 species which have either expanded their ranges within Europe under human influence (naturalized European species) or are of non-European origin (exotic species). The latter group consists of 580 species (37%) which form a diverse group in terms of their taxonomic composition and geographic origin. The exotics are represented by 113 families, of which the Compositae, Rosaceae and Gramineae are most important. The ratio of species to families is low. Most exotic species in Europe originate from the Americas and Asia. Countries of southern Europe have a higher relative number of exotics in their non-native flora than northern ones. The species-range size distribution differs between naturalized European and exotic species; the latter are on average more widespread than the naturalized.     

Phylogeny of the order Rodentia inferred from structural analysis of short retrotransposon B1

A large-scale study of short retroposon (SINE) B1 has been conducted in the genome of rodents from most of the known families of this mammalian order. The B1 nucleotide sequences of rodents from different families exhibited a number of characteristic features including substitutions, deletions, and tandem duplications. Comparing the distribution of these features among the rodent families, the currently discussed phylogenetic relationships were tested. The results of analysis indicated (1) an early divergence of Sciuridae and related families (Aplodontidae and Gliridae) from the other rodents; (2) a possible subsequent divergence of beavers (Castoridae); (3) a monophyletic origin of the group Hystricognathi, which includes several families, such as porcupines (Hystricidae) and guinea pigs (Caviidae); (4) a possible monophyletic origin of the group formed by the remaining families, including six families of mouselike rodents (Myodonta). Various approaches to the use of short retroposons for phylogenetic studies are discussed.