Food resource partitioning and trophic morphology of Brevoortia gunteri and B. patronus

The menhadens Brevoortia gunteri and B. patronus are sympatric and morphologically similar. The two species are planktophagous and exhibited significant ( P < 0·0001) food resource partitioning, with phytoplankton predominating in B. patronus stomachs and zooplankton in B. gunteri. The branchial apparatus of both species is of the typical alosine form. Brevoortia patronus has significantly more branchiospinules per mm (=19·47) and significantly longer gill rakers (=13·35 mm) than B. gunteri (=14·11, =12·01 mm respectively). B. patronus is characterized by a gill raker system forming a fine-meshed filter capable of retaining smaller food items. The results support the hypothesis that food resource partitioning is related to different morphological features of the branchial apparatus.     

不同颌间牵引固定方案治疗单纯髁状突骨折的临床疗效比较

目的:研究不同颌间牵引固定方案治疗单纯髁状突骨折的临床疗效,为临床治疗提供依据。方法:选取2010年1月到2015年1月我院收治的单纯髁状突骨折患者50例,按照随机数字表法将患者分为A组和B组,A组给予牵引钉植入牵引固定方案治疗,B组给予牙弓夹板行颌间牵引固定方案治疗,比较两组操作时间、术后最大开口度、五个时间点软垢指数(DI)、牙龈指数(GI)以及社区牙周需要治疗指数(CPITN),并比较两组临床疗效。结果:A组操作时间显著短于B组(P0.05);术后最大开口度和颞下颌关节情况无显著差异(P0.05);A组第2次、3次、4次以及5次的DI、GI和CPITN均显著优于B组(P0.05);两组面型偏斜、咀嚼良好、咬合关系、关节弹性、开口偏斜以及关节牙痛比较均无显著差异(P0.05)。结论:牵引钉植入与牙弓夹板颌间牵引固定均可以较好改善患者骨折情况,但牵引钉植入术对患者伤害小,操作时间短,术后患者软垢和牙龈情况均较好。     

Ventilation of the branchial chambers in the amphibious West African freshwater crab,Sudanonautes (Convexonautes) aubryi monodi (Balss, 1929) (Brachyura,Potamonautidae)

The anatomy of the respiratory system of the savanna-zone African freshwater crab, Sudanonautes (Convexonautes) aubryi monodi [Balss, 1929], has been examined and has been found to be adapted for both aerial and aquatic gas exchange. The activities of the scaphognathites and the directions of flow of the ventilatory stream have been recorded in stressed, active and resting specimens during their exposure to a wide range of conditions from deep water to dry land.Ventilation of the branchial chambers during aquatic gas exchange in Sudanonautes kept in deep water is shown to consist of a rapid, predominantly forward water flow similar to that of fully-aquatic species. Ventilation of the branchial chambers during aerial gas exchange in Sudanonautes on land is shown to consist of a relatively slow forward air flow. This flow is continuous in post-operative crabs, pulsatile in active crabs and completely immobile in resting crabs.A second method of ventilation of the branchial chambers during aerial gas exchange is shown to consist of a pulsatile reversed air flow. This occurs (1) when Sudanonautes is kept in very shallow water and active or stressed; (2) when it has recently moved on to land; and (3) when it is completely immersed and exhibiting aerial gas exchange under water. The unusual phenomenon of aerial gas exchange under water is reported here for the first time in any species of crab.Bimodal ventilation of the branchial chambers occurs in stressed or active crabs partly immersed in shallow water. This consists of an alternation between forward water flow and reversed air flow.The morphology of the branchial chambers in Sudanonautes, and observational data on the patterns of ventilation of the branchial chambers, are discussed in relation to those described for other air-breathing decapod crustaceans.     

Roles of the Foxj1 and Inv genes in the left-right determination of internal organs in mice

In Foxj1 knockout mice, half show situs solitus while the other half show situs inversus, which means a random determination of the left-right axis. In contrast, the inv mutant mice show a mirror-image configuration of the internal organs, which means a reversal of the left-right axis. Although these two mutant mice have primary cilia on the nodal cells, their phenotypes are different in laterality determination. We thus made Foxj1/inv double mutant mice and analyzed their phenotype. We found the phenotypes of Foxj1/inv double mutant mice to be more similar to those of the Foxj1 mutant mice than those of the inv mutant mice. We also found right pulmonary isomerism to be a major phenotype of the Foxj1 mutant mice and the Foxj1/inv double mutant mice, which is likely due to the absence of the Pitx2 expression at both lateral plate mesoderms. These results indicate that a random signal of laterality (Foxj1) is dominant over the reversal signal of laterality (Inv).     

<Emphasis Type="Italic">Hoxa3</Emphasis> and signaling molecules involved in aortic arch patterning and remodeling

Anomalies of the aortic arch have long been of anatomicoclinical interest. Recent studies on gene-targeted mice have identified the candidate genes that are involved in the patterning and remodeling of the pharyngeal arch arteries. In this review, we discuss our present knowledge with regard to the signaling molecules that regulate specific aspects of arch artery development. We focus first on Hoxa3, because it plays a critical role in the regulation of the differentiation of the third pharyngeal arch. Hoxa3 is expressed by the neural crest cells that originate from the rhombomeres, viz., (r)5, r6, and r7, and populate the third pharyngeal arch; it is also expressed in the third pharyngeal pouch. In Hoxa3 homozygous null mutant mice, the third arch artery degenerates bilaterally at embryonic day 11.5, resulting in the malformation of the carotid artery system. Complex combinatorial signals among the neural crest cells, pharyngeal mesoderm, ectoderm, and pouch endoderm are required for the proper development of the arch arterial system. Therefore, we highlight the numerous signaling pathways and individual genes expressed by the ectomesenchymal neural crest cells and also by the other epithelial and mesodermal cells of the pharynx. Defects in these genes result in malformations of the arch artery derivatives. This review should deepen our understanding of congenital human syndromes with abnormal patterns of pharyngeal arch arteries.     

Variation in Gillraker Number During Growth of the Sea Bass, Dicentrarchus labrax (Perciformes: Moronidae), Reared at Different Salinities

A marked salinity-related decrease in gillraker number in sea bass samples during growth was documented. All specimens share the same genetic stock and rearing conditions were constant during early ontogeny. Variation in gillraker number could be related to the ecophenotypism of this character but selection can not be excluded. Results obtained from reared specimens were compared with those reported in the literature and with data collected from wild stocks. Attention is focused on the pitfalls that the use of this character may have on the taxonomy of fish species.     

Genomic screen for genes involved in mammalian craniofacial development

Using a subtractive hybridisation approach, we enriched for genes likely to play a role in embryonic development of the mammalian face and other structures. This was achieved by subtracting cDNA derived from adult mouse liver from that derived from 10.5 dpc mouse embryonic branchial arches 1 and 2. Random sequencing of clones from the resultant library revealed that a high percentage correspond to genes with a previously established role in embryonic development and disease, while 15% represent novel or uncharacterised genes. Whole mount in situ hybridisation analysis of novel genes revealed that approximately 50% have restricted expression during embryonic development. In addition to expression in branchial arches, these genes showed a range of expression domains commonly including neural tube and somites. Notably, all genes analysed were found to be expressed not only in the branchial arches but also in the developing limb buds, providing support for the hypothesis that development of the limbs and face is likely to involve analogous molecular processes.     

Formation of the inner branchiostegal cuticle of the blue crab,Callinectes sapidus

The noncalcified inner branchiostegal cuticle, which lines the branchial chamber, was examined histologically and ultrastructurally over the molt cycle in the blue crab, Callinectes sapidus. In intermolt crabs (stage C₄) the epithelium underlying the inner cuticle is cuboidal and has abundant intercellular spaces and a prominent basement membrane. Apolysis occurs at stage D₀ and dissolution of the cuticle is accompanied by the formation of numerous lysosomes in the epithelium. During stage D₁, cells increase in height, apical mitochondria become more abundant, and the cuticle continues to be resorbed. An epicuticle is formed in early D₂, arising from a fusion of small subunits apparently attached to short apical microvilli. Cuticle deposition continues through D₂ and is complete by stage D₃. By the time cuticle deposition is complete, the epithelium has become extremely columnar and cells are filled with bundles of microtubules. In stage D₄, an amorphous electron‐dense core appears in the microtubule‐filled cells, which are attached to the cuticle at their apical end and anchored to their basement membrane at the basal surface. These microtubule‐filled cells persist through ecdysis, stage E, but during stage A₁ the cores disappear and some organelles begin to reappear in the cytoplasm. By stage A₂, the cells return to the cuboidal morphology seen in intermolt and remain so throughout the remainder of the molt cycle. This new pattern of cuticle deposition resembles that observed in the gills of crustaceans in that the cuticle is uncalcified and there is no postecdysial cuticle formation. However, instead of apolysis being delayed until just before ecdysis, the inner cuticle is formed during the first half of premolt, allowing the epithelial cells time to differentiate into a morphology that provides tensile strength for the stress of ecdysis. These new observations demonstrate that cuticle formation can follow very diverse structural and temporal patterns. In order to integrate and coordinate these diverse patterns, it is suggested that a suite of feedback mechanisms must be present. J. Morphol. 240:267–281, 1999. © 1999 Wiley‐Liss, Inc.