Functional morphology and ultrastructure of mouthparts in unfed water mite larvae Piona carnea (Koch, 1836) (Acariformes: Pionidae)

Mouthparts of unfed larvae Piona carnea (Koch, 1836) (Acariformes: Pionidae) were studied on whole-mount preparations, semi-thin sections and with TEM and SEM methods. The mouth apparatus is incorporated within the pseudotagma, gnathosoma, composed of the infracapitulum and of the chelicerae resting on the roof of the latter. The gnathosoma inclines to the long axis of the body and is inserted at its base into the idiosoma by the circumcapitular fold. The basal cheliceral segments are long and fused. An anterior projection, the proposed fused fixed digits, protrudes from the distal end of the basal cheliceral segment forward between the movable digits. The movable digits are always found in protruded position, strongly curved upward and show a groove on their inner sides. The ventral wall of the infracapitulum is made of the mentum posterior and the malapophyses anterior to the palp articulation. The malapophyses are squeezed between the large palps and envelope the distal portion of the chelicerae from the sides. The ventral portion of the fused malapophyses are provided with a characteristic ventral cuticular fork of unknown function. Each malapophysis terminates by a flexible lateral lip provided by several rigid jags looking posterad. The palps face downward and backward, and bear on the tibia the large curved palpal claws turned laterad. The palp femur bears on the ventral aspect a characteristic wide spade-like projection provided with its own muscles originating on the dorsal wall of the femur. The labrum is a thick cuticular arrow-like structure protruding forward into the preoral cavity, whereas the cervix is a thin weakly sclerotized plate. The particular labral valve projects forward from the dorsal basis of the labrum into the preoral cavity. The labrum and the cervix are provided by their own small labral and cervical muscles originating on the cervical apodemes. The pharynx is totally separated from the ventral wall of the infracapitulum and is devoid of ventral dilators. The dorsal pharyngeal dilators originate on the thick and sclerotized capitular apodeme and, posteriorly, on the paired cuticular branches, capitular apodemes, which end freely in the body cavity and are combined with the common salivary duct. The short sigmoid pieces serve for origin of the levator muscles of the chelicerae. Retraction of the gnathosoma and the chelicerae is mediated by several sets of muscles originating on the dorsal plate.     

Whole mount nuclear fluorescent imaging: Convenient documentation of embryo morphology

Here, we describe a relatively inexpensive and easy method to produce high quality images that reveal fine topological details of vertebrate embryonic structures. The method relies on nuclear staining of whole mount embryos in combination with confocal microscopy or conventional wide field fluorescent microscopy. In cases where confocal microscopy is used in combination with whole mount nuclear staining, the resulting embryo images can rival the clarity and resolution of images produced by scanning electron microscopy (SEM). The fluorescent nuclear staining may be performed with a variety of cell permeable nuclear dyes, enabling the technique to be performed with multiple standard microscope/illumination or confocal/laser systems. The method may be used to document morphology of embryos of a variety of organisms, as well as individual organs and tissues. Nuclear stain imaging imposes minimal impact on embryonic specimens, enabling imaged specimens to be utilized for additional assays. genesis 2012. © 2012 Wiley Periodicals, Inc.     

The pattern of cell wall deterioration in lignocellulose fibers throughout enzymatic cellulose hydrolysis

Cell wall deterioration throughout enzymatic hydrolysis of cellulosic biomass is greatly affected by the chemical composition and the ultrastructure of the fiber cell wall. The resulting pattern of cell wall deterioration will reveal information on cellulose activity throughout enzymatic hydrolysis. This study investigates the progression and morphological changes in lignocellulose fibers throughout enzymatic hydrolysis, using (transmission electron microscopy) TEM and field emission scanning electron microscopy (FE‐SEM). Softwood thermo‐mechanical pulp (STMP) and softwood bleached kraft pulp (SBKP), lignocellulose substrates containing almost all the original fiber composition, and with lignin and some hemicellulose removed, respectively, was compared for morphology changes throughout hydrolysis. The difference of conversion between STMP and SBKP after 48 h of enzymatic hydrolysis is 11 and 88%, respectively. TEM images revealed an even fiber cell wall cross section density, with uneven middle lamella coverage in STMP fibers. SKBP fibers exhibited some spaces between cell wall and lamella layers due to the removal of lignin and some hemicellulose. After 1 h hydrolysis in SBKP fibers, there were more changes in the fiber cross‐sectional area than after 10 h hydrolysis in STMP fibers. Cell wall degradation was uneven, and originated in accessible cellulose throughout the fiber cell wall. FE‐SEM images illustrated more morphology changes in SBKP fibers than STMP fibers. Enzymatic action of STMP fiber resulted in a smoother fiber surface, along with fiber peeling and the formation of ribbon‐disjunction layers. SBKP fibers exhibited structural changes such as fiber erosion, fiber cutting, and fiber splitting throughout enzymatic hydrolysis. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 2012     

Fibroblast growth factor 2 and protein kinase C alpha are involved in syndecan-4 cytoplasmic domain modulation of turkey myogenic satellite cell proliferation

Syndecan-4 core protein is composed of extracellular, transmembrane, and cytoplasmic domains. The cytoplasmic domain functions in transmitting signals into the cell through the protein kinase C alpha (PKCα) pathway. The glycosaminoglycan (GAG) and N-linked glycosylated (N-glycosylated) chains attached to the extracellular domain influence cell proliferation. The current study investigated the function of syndecan-4 cytoplasmic domain in combination with GAG and N-glycosylated chains in turkey muscle cell proliferation, differentiation, fibroblast growth factor 2 (FGF2) responsiveness, and PKCα membrane localization. Syndecan-4 or syndecan-4 without the cytoplasmic domain and with or without the GAG and N-glycosylated chains were transfected or co-transfected with a small interfering RNA targeting syndecan-4 cytoplasmic domain into turkey muscle satellite cells. The overexpression of syndecan-4 mutants increased cell proliferation but did not change differentiation. Syndecan-4 mutants had increased cellular responsiveness to FGF2 during proliferation. Syndecan-4 increased PKCα cell membrane localization, whereas the syndecan-4 mutants decreased PKCα cell membrane localization compared to syndecan-4. However, compared to the cells without transfection, syndecan-4 mutants increased cell membrane localization of PKCα. These data indicated that the syndecan‐4 cytoplasmic domain and the GAG and N-glycosylated chains are critical in syndecan-4 regulating satellite cell proliferation, responsiveness to FGF2, and PKCα cell membrane localization.     

A forgotten homology supporting the monophyly of Tracheata: The subcoxa of insects and myriapods re-visited

The current discussion about the relationships of higher arthropod taxa has led to a conflict between the traditional Tracheata (=Atelocerata) concept (hexapods united with myriapods), the Tetraconata concept (hexapods united with crustaceans, excluding myriapods), and the Paradoxopoda or Myriochelata concept (myriapods united with cheliceratans), with major contradictions between morphological and molecular data. We have analyzed a character set which apparently has completely vanished from the recent debate, namely the equipment of the trunk pleura of myriapods and insects with a characteristic set of concentric sclerites around the leg base and accompanying muscles. Based on the work of Heymons (1899) these sclerites were thought to be remains of the first appendage article, then denominated “subcoxa”. We have re-visited this old idea and show the arrangement of the much discussed pleural structures by SEM for the first time. Obviously a characteristic pattern of concentric pleural plates around the leg-base is present in all major myriapod taxa, including for the first time evidence for their presence in Progoneata. Because of their equal structure and orientation, the pleural sclerites present in entognathous and ectognathous insects may be derived from the same ground pattern. We conclude that the pleurites of Hexapoda and Myriapoda seem to be homologous structures, and there is evidence that the “subcoxa” of Tracheata is homologous with the coxa of crustaceans. Since no other arthropods show these sclerites, the transformation of the crustacean coxa to the pleural region in myriapods and insects is probably a synapomorphy congruent with the traditional Tracheata-hypothesis. Further investigations of recently published molecular work using the phylogenetic network software SplitsTree V.4 indicate that information content of several data sets is not convincing.     

柳属的叶表皮微形态特征及其分类学意义

研究了29种柳属( Salix )植物在扫描电镜下的叶表皮微形态特征.结果表明:柳属的角质层蜡质纹饰可以划分为:痂状蜡质层,壳状平滑蜡质层,具凸起颗粒的蜡质层,具颗粒的蜡质层,锥形纤维体和鳞片状纤维体6种类型.其中锥形纤维体和鳞片状纤维体均为柳属所特有的蜡质类型,后者为前者的变型,这两种蜡质纹饰类型多见于较为进化的皱纹柳亚属和黄花柳亚属,故推测其可能为柳属中较为进化的性状.研究还发现气孔有外拱盖扁平和隆起呈脊状2种类型.而气孔外拱盖内缘为浅波状的类型仅见于高山和北极的类群中,因而推测该类型可能同高山和极地的低温等环境有关.气孔外拱盖的形态及其角化的情况以及蜡质类型是稳定的鉴别特征,对于柳属植物,尤其是一些表型相似的种类有很好的鉴别作用,但对于组、亚属的界定作用不大.     

黑龙江椴树属植物叶表皮形态学观察

利用扫描电子显微镜对紫椴（Tilia amurensis Rupr.）及糠椴（T. mandshurica Rupr.et Maxim.）叶片的微观形态结构特征进行观察,并进行微观形态结构的比较研究。研究结果表明紫椴与糠椴叶片上表皮微观形态相同,而下表皮气孔器的形态类型、蜡质纹饰和角质膜的形态特征、单位面积上星状毛的数量均表现出很大的差异。这些微观形态差异可作为区分紫椴和糠椴的分类学依据。     

Pollen morphology in <Emphasis Type="Italic">Lysipomia</Emphasis> (Campanulaceae: Lobelioideae) and interpretation of shape artifacts

The pollen of 32 species of Lysipomia was examined by light, scanning, and transmission electron microscopy. Two pollen types occur in the genus: 3-colporate and 6-colporate. The 3-colporate condition occurs in only two species, L. laciniata and L. pumila. The remaining 30 species are 6-colporate, a condition known from only one other genus in the Campanulaceae. Surface sculpturing among the species is uniformly striate. Pollen shape was highly variable within a single individual in comparisons of pollen gathered from herbarium specimens, FAA preserved material collected in the field, and fresh pollen from cultivated individuals grown from seed. Shape may change from oblate spheroidal to subprolate as a result of drying time and temperature, and should not be used as a morphological character in systematic studies if infraspecific variation is seen. When fresh or preserved pollen is not available, rehydrated pollen should be compared to reduce the possibility of inadvertent artifact production confounding the analysis of morphological data.     

Observations of serotonin and FMRFamide-like immunoreactivity in palp sensory structures and the anterior nervous system of spionid polychaetes

Evidence suggests that ciliated sensory structures on the feeding palps of spionid polychaetes may function as chemoreceptors to modulate deposit-feeding activity. To investigate the probable sensory nature of these ciliated cells, we used immunohistochemistry, epi-fluorescence, and confocal laser scanning microscopy to label and image sensory cells, nerves, and their organization relative to the anterior central nervous system in several spionid polychaete species. Antibodies directed against acetylated alphatubulin were used to label the nervous system and detail the innervation of palp sensory cells in all species. In addition, the distribution of serotonin (5-HT) and FMRFamide-like immunoreactivity was compared in the spionid polychaetes Dipolydora quadrilobata and Pygospio elegans. The distribution of serotonin immunoreactivity was also examined in the palps of Polydora cornuta and Streblospio benedicti. Serotonin immunoreactivity was concentrated in cells underlying the food groove of the palps, in the palp nerves, and in the cerebral ganglion. FMRFamide-like immunoreactivity was associated with the cerebral ganglia, nuchal organs and palp nerves, and also with the perikarya of ciliated sensory cells on the palps.     

Volume and morphology changes of a bdelloid rotifer species (Macrotrachela quadricornifera) during anhydrobiosis

Following a study on the changes occurring in a bdelloid species (Macrotrachela quadricornifera, Rotifera, Bdelloidea) when entering anhydrobiosis, we investigated the changes in morphology, including weight and volume during the transition from the active hydrated to the dormant anhydrobiotic state by scanning electron microscopy, confocal microscopy and light microscopy. We compared sizes and morphologies of hydrated extended, hydrated contracted and anhydrobiotic specimens. Bdelloid musculature is defined: longitudinal muscles are contracted in the hydrated contracted animal (head and foot are retracted inside the trunk), but appear loose in the anhydrobiotic animal. When anhydrobiotic, M. quadricornifera appears much smaller in size, with a volume reduction of about 60% of the hydrated volume, and its internal organization undergoes remarkable modifications. Internal body cavities, clearly distinguishable in the hydrated extended and contracted specimens, are no longer visible in the anhydrobiotic specimen. Concomitantly, M. quadricornifera loses more than 95% of its weight when anhydrobiotic; this is more than expected from the volume reduction data and could indicate the presence of space-filling molecular species in the dehydrated animal. We estimate that the majority of body mass loss and volume reduction can be ascribed to the water loss from the body cavity during desiccation.