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Ali Denisov
Ali Denisov


The fine structure of a spider myo-apodeme junction is described, and discussed in terms of other arthropod muscle attachments. This is contrasted with the situation in the venom gland, equipped with muscle fibers that control expulsion of the secreted material. The latter involves a cell-free collagenous matrix, lying between the muscle cells and the sheath of the gland. As in other arthropods, skeletal fibers are attached to the apodeme cuticle via specialized epidermal cells, containing oriented microtubules. Interdigitations between these cells and muscle, basally, and cuticle, apically, are described. Extracellular tonofibrillae described elsewhere are inconspicuous in the apodeme cuticle.


During Drosophila embryogenesis, the beta 1 tubulin gene (beta Tub56D) is expressed in the CNS and PNS as well as in the apodemes. In this report we determine the regulation of beta 1 tubulin gene expression during formation of the attachment sites of the somatic muscles, the apodemes. The process was analysed in transgenic flies carrying beta 1 enhancer-hsp70 promoter-lacZ fusion constructs. Expression is first detected at late stage 13 and remains until hatching. By deletion analysis of the intron we identified a 14-bp element present in three copies. This element represents a classical enhancer, as it acts on a heterologous promoter. Separate fragments containing the respective elements yield nearly identical expression patterns, and no cooperativity was observed between the three copies. Thus, the expression of the beta 1 tubulin gene in the apodemes is under control of redundant enhancer elements. Double staining for beta 1 tubulin gene expression in apodemes and for beta 3 tubulin gene expression in muscles allowed us to correlate apodeme and muscle formation. Cells of the apodemes that are in contact with their corresponding muscles show expression of the reporter gene as monitored by antibody staining.

An apodeme of the mandible that provides attachment for the mandibular adductor muscle. In mosquito larvae, attached to the mesal end or to a posterior projection of the mesal end of the ventral arm of the U-shaped rod.

apodeme (ap'-o-deme). One of the ingrowths from the exoskeleton of many arthropods that provide points of muscle attachment, such as an invagination of the body wall of an arachnid, an inward deflection of a sclerite of a merostome, a downward projection from the dorsal interior of a thoracic segment of a trilobite, or an infold of the exoskeleton of a crustacean.

Female: Length 140 to 175 microns, width 75 to 84 microns. Idiosoma ovoid or nearly pyriform; dorsal shield and plates faintly sclerotized, with indistinct punctures. Propodosoma lacking pseudostigmatic sensilla; two pairs of long, attenuate setae, verticals V1 and scapulars Sce. V1 setae shorter than Sce, about 1/4 longer than distance between bases of setae Sce. Ventral apodemes I forming Y-shaped structure with anterior median apodeme (a conspicious transverse band crossing the thorax in front of the scutellum), not joining transverse apodeme. Apodemes III weakly extending laterad to bases of trochanters III. Apodemes IV extending to bases of trochanters IV. Posterior median apodeme rudimentary, sometimes as faintly formed Y-shaped structure. Leg I robust with single hooked claw. Legs II and III each with paired claws. Leg IV stubby, widely spaced; femur-genu and tibiotarsus functioning as one segment; tibiotarsus IV two times as long as broad; femur-genu broader than long, with three setae unequal length; tibiotarsus abruptly narrowed, almost straight, about two times as long as broad. For a more complete description see Delfinado-Baker and Baker (1984).

Male: Length 125 to 136 microns, width 60 to 77 microns. Similar to female except for sexual differences. Apodemes III to IV not developed, barely discernible. Posterior median apodeme indistinct, sometimes forming weak Y-shaped structure. Apodemes V present as weakened transverse apodeme barely discernible. Leg I more robust than others. Leg IV short, about 3/4 as long as leg III, without claw; trochanter large, slightly longer than wide, with seta; femur-genu slightly more than two times as long as wide, without flanges, three setae of unequal length; tibiotarsus nearly straight, slightly shorter than femur-genu; apical with slender pointed solenidion and 1 very long seta. Males and nymphs are difficult to separate from other known species.

Tergosternal muscles. Paired, wide symmetrical M5 connecting anterolateral parts of epandrium to lateral thickenings of dorsal bridge of paramere in the point of connection of pm db with gonocoxites (= gonocoxal apodeme) (Figure 6B, C). Lateral thickenings of dorsal bridge of paramere interpreted as gonocoxites according to attachment sites of muscles M5.

Among these families only Tanyderidae are characterized by ejaculator muscles M23 (in addition to muscles M30 and M31, present in other families). Muscles M23 connect only sclerites or membranes of aedeagal complex consisting of ejaculatory apodeme and aedeagus. Up to now these muscles were recorded in the only one nematocerous family, Trichoceridae, and in Brachycera (as M32 in Ovtshinnikova 1989). Based on our data one can suppose that muscles M23 are present in the groundplan of the Diptera.

It can be assumed that muscles M30 and M31 of Tanyderidae, attached to different parts of the ejaculatory apodeme, have the opposite functions of muscles M30 and M31 of Blephariceridae and Bibionidae and most of Brachycera, muscles M31 of Psychodidae and Ptychopteridae. Muscles M30 of Tanyderidae are, probably, protractors, muscles M31 of Tanyderidae are, probably, retractors as in Trichoceridae (Ovtshinnikova 1989). Protractor muscles in these families are usually wide and fan-shaped, their attachment sites occupy a wide surface of the ejaculatory apodeme, regardless of the origin of the muscles (muscles M30 or M31). At the same time, the other side of the protractor muscles of Tanyderidae is attached to the gonocoxites, therefore the muscles are designated as M30, as well as in the most other families (including Brachycera). Retractors are narrower and often connect to the base of the ejaculatory apodeme. In the Tanyderidae these muscles are connected to parameres, and are designated as M31, in other families these muscles are associated with gonocoxite apodemes or gonocoxites and are designated as M30. Therefore, in this case we assume a complete changing of the functions of these paired antagonist muscles.

apodeme: Internal sclerite that serves as an attachment site for muscles. Most commonly used (as "coxal apodeme") to describe elements of coxae fused to the ventral body in Acariformes (coxae are free and not fused to the body in Parasitiformes), and may be variously referred to as ventral, sternal, anterior, or posterior.

coxa: In Parasitiformes, most basal leg segment (or podomere) forming a joint with the body. Areas delimited by coxal apodemes are called coxal fields in Astigmata or coxisternal plates in Prostigmata.

The pleural suture marks the location of an internal ridge of exoskeleton (an apodeme) that strengthens the sides of the thorax. Ventrally, this apodeme forms a point of articulation with the basal leg segment (the coxa). In thoracic segments that bear wings, the pleural apodeme runs dorsally into the pleural wing process, a finger-like sclerite that serves as a pivot or fulcrum for the base of the wing.

Grasshoppers (Schistocerca gregaria) will normally spend 300 milliseconds storing up energy in their muscles, apodemes, and exoskeletons, although they have to jump more quickly, and perhaps less efficiently, to evade predators. Bullfrogs (Lithobates catesbeiana), on the other hand, normally spend only 50 milliseconds before making a leap, for instance to pounce toward prey.

3D reconstruction and segmentation of the mandible muscles and apodemes of a Melissotarsus worker. a Anterior, b lateral, and c posterior views; (left) muscles and apodemes, (right) apodemes only. AdM, closer muscle (orange); AbM, opener muscle (light blue); AdAp, closer apodeme (red); AbAp, opener apodeme (dark blue)

Expression Patterns of Genes that Cause a Gain-of-Function Muscle PhenotypeLateral views of embryos at stage 11 (M), stage 13 (A, C, E, G, I, K, and N), and stage 16 (B, D, F, H, J, and L) that were stained with transcript-specific anti-sense RNA probes or with anti-Toll antibodies (A and B). Note the expression of Toll (A and B) in segment border cells, sdc (LD08230) (C and D) in trachea, segment border cells, and the differentiated apodemes, CG3563 (LD15689) (E and F) in the apodeme precusor cells at the segment border, CG13913 (RE53394) (G and H) and CG5008/gnbp3 (SD21560) (I and J) in a subset of apodeme precursors and cells of the epidermis, CG14713/14714 transcripts (AT17253) (K and L) in the dorsal and ventral epidermis around the segment border, and pxb (SD26190) (M and N) in intrasegmental epidermal stripes. 041b061a72


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