Mantle displays of freshwater mussels elicit attacks from fish

1. Gravid females of some North American freshwater mussel species (Bivalvia: Unionidae) display highly modified mantle margins and other reproductive structures which mimic small fish, terrestrial insects, or aquatic macro-invertebrates. We report the responses of fish to these lures, based on the results of laboratory encounters between the following pairs of displaying mussels and fishes: Lampsilis cardium and Micropterus coosae; L . perovalis and M . coosae; and Villosa nebulosa and Percina nigrofasciata . In all three encounters, the lures elicited attacks from fish.
2. Encounters between Lampsilis spp. and M. coosae resulted in gill infestations of the fish by larval mussels, which are obligate parasites on fish. An encounter between V . nebulosa and P . nigrofasciata did not result in infestation.
3. The use of these lures to attract fish may greatly increase the chances of parasite/host encounters and may also reduce the chances of infestation of unsuitable hosts.     

Changes in the timing of mantle formation and larval life history traits in linguliform and craniiform brachiopods

The distribution of embryonic and larval mantles is documented in linguliform and craniiform brachiopods. Criteria are presented for identifying these mantle types. The mantle type is related to planktotrophic and lecithotrophic larval life history patterns. In the Linguliformea and Craniiformea, all Lower Palaeozoic families with adequate preservation had larval mantles, indicating the presence of a planktotrophic larva. Heterochronic changes in the time of mantle origin, from the larval to the embryonic stage of development, has occurred several times. In the Lingulidae this change appears to have taken place at about the time the family originated in the Devonian and has been retained in extant genera. The family Discinidae has also retained a planktotrophic larval stage from the Lower Palaeozic to the present. The extant genus Crania in the Craniidae has a short-lived lecithotrophic larva that lacks a mantle. Through the Lower Jurassic, this family had planktotrophic larvae with a larval shell. During the Upper Jurassic, genera with a lecithotrophic larva that lacked a larval shell began to appear; however, the last genera in this family with a planktotrophic larva and a larval shell did not become extinct until the Tertiary.     

Form and function of tentacles in pteriomorphian bivalves

Tentacles are remarkable anatomical structures in invertebrates for their diversity of form and function. In bivalves, tentacular organs are commonly associated with protective, secretory, and sensory roles. However, anatomical details are available for only a few species, rendering the diversity and evolution of bivalve tentacles still obscure. In Pteriomorphia, a clade including oysters, scallops, pearl oysters, and relatives, tentacles are abundant and diverse. We investigated tentacle anatomy in the group to understand variation, infer functions, and investigate patterns in tentacle diversity. Six species from four pteriomorphian families (Ostreidae, Pinnidae, Pteriidae, and Spondylidae) were collected and thoroughly investigated with integrative microscopy techniques, including histology, scanning electron microscopy, and confocal microscopy. Tentacles can be classified as middle fold tentacles (MFT) and inner fold tentacles (IFT) according to their position with respect to the folds of the mantle margin. While MFT morphology indicates intense secretion of mucosubstances, no evidence for secretory activity was found for IFT. However, both tentacle types have appropriate ciliary distribution and length to promote mucus transportation for cleaning and lubrication. Protective and sensory functions are discussed based on different lines of evidence, including secretion, cilia distribution, musculature, and innervation. Our results support the homology of MFT and IFT only for Pterioidea and Ostreoidea, considering their morphology, the presence of ciliated receptors at the tips, and branched innervation pattern. This is in accordance with recent phylogenetic hypotheses that support the close relationship between these superfamilies. In contrast, major structural differences indicate that MFT and IFT are probably not homologous across all pteriomorphians. By applying integrative microscopy, we were able to reveal anatomical elements that are essential for the understanding of homology and function when dealing with such superficially similar structures.     

Synthesis and Microdiffraction at Extreme Pressures and Temperatures

High pressure compounds and polymorphs are investigated for a broad range of purposes such as determine structures and processes of deep planetary interiors, design materials with novel properties, understand the mechanical behavior of materials exposed to very high stresses as in explosions or impacts. Synthesis and structural analysis of materials at extreme conditions of pressure and temperature entails remarkable technical challenges. In the laser heated diamond anvil cell (LH-DAC), very high pressure is generated between the tips of two opposing diamond anvils forced against each other; focused infrared laser beams, shined through the diamonds, allow to reach very high temperatures on samples absorbing the laser radiation. When the LH-DAC is installed in a synchrotron beamline that provides extremely brilliant x-ray radiation, the structure of materials under extreme conditions can be probed in situ. LH-DAC samples, although very small, can show highly variable grain size, phase and chemical composition. In order to obtain the high resolution structural analysis and the most comprehensive characterization of a sample, we collect diffraction data in 2D grids and combine powder, single crystal and multigrain diffraction techniques. Representative results obtained in the synthesis of a new iron oxide, Fe₄O₅ ¹ will be shown.     

Relationships between magmatism and lithosphere-asthenosphere structure in the Western Mediterranean and implications for geodynamics

Shear-wave (V _S ) tomography along transects across the Western-Central Mediterranean area reveals heterogeneous lateral and vertical physical characteristics in the lithosphere-asthenosphere system (LAS). A 50 km thick low velocity layer (LVL), with V _S ∼ 4.0–4.2 km/sec, typical of low rigidity fluid-bearing mantle material, is observed at a depth of about 70–120 km from offshore Provence, to Sardinia and the Central Tyrrhenian Sea. This LVL, enclosed between higher velocity mantle rocks, rises to a depth of less than 30 km below the recent and active volcanoes of Central Italy and the Southern Tyrrhenian Sea, where a maximum in the heath flow is observed. The LVL is absent beneath Southeastern France and the northern border of the African foreland. In the Balearic Sea-Sardinia-Central Tyrrhenian section, the depth of LVL corresponds to pressure conditions of minimum temperature of peridotite+CO₂+H₂O solidus, consistent with conditions where fluid loss from the slab and mantle flow over the subducting plate favor significant melt generation above steep, west-dipping subduction zones. It is suggested that LVL in the Balearic-Tyrrhenian domains is the result of mantle contamination and melting left behind by the eastward retreating Adriatic-Ionian subducting plates from Oligo-Miocene to present. This layer also marks a discontinuity between the lithospere and underlying mantle behind the subduction zone, favoring detachment and westward drift of the lithosphere, and consequent opening of backarc basins. These data support the hypothesis that the orogenic Oligocene to Quaternary volcanism in the Western Mediterranean area is the effect of shallow mantle processes, and argue against the presence of deep mantle plumes. A shallow-mantle origin is also suggested for the EM1-type Plio-Quaternary anorogenic magmatism in Sardinia and for the FOZO-DMM-type magmatism on the northern margin of the African foreland.      

Inherited abnormal growths on the mantle of Biomphalaria glabrata

Studies involved tissue growths in four different abnormal locations associated with the mantle of Biomphalaria glabrata: on the medial surface of the pseudobranch, projecting from the end of the dorsal ridge, inside the aperture on the right side, and at the base of the rectal fold in the ventral mantle chamber. Each type of growth was observed in only one or a few stocks of B. glabrata. Laboratory observations through several generations, with selection and reproduction of isolated snails by self-fertilization, suggested the tendency for formation of each of these types of growths was inherited.     

对黑蜗牛生物学特性的初步研究

利用对比观察法,研究黑蜗牛的形态结构、生殖特点、死亡原因,发现黑蜗牛的螺旋贝壳短,只有壳顶和两个螺层,体螺层不能完全容纳软体,螺旋贝壳中碳酸钙含量约为60．3％,易软化。体背上生长着外套膜和外壳膜,外套膜在螺旋贝壳内包裹着内脏囊,外壳膜覆盖在螺旋贝壳的表面,能向不同方向伸展。壳口处的外壳膜上有排泄孔,排泄孔与外套膜上的呼吸孔连通,具有呼吸、排泄粪便和排泄尿液的多种功能。证明黑蜗牛是一种新的软体动物——最原始的蜗牛,也是陆生软体动物贝壳退化成内壳的过渡物种。隶属于琥珀蜗牛科（Zonitidae）,夏威夷琥珀蜗牛属（Hawaiia）,沂水琥珀蜗牛种（Hawaiia yishuiusculeLi）。     

A key role for EZH2 in epigenetic silencing of HOX genes in mantle cell lymphoma

The chromatin modifier EZH2 is overexpressed and associated with inferior outcome in mantle cell lymphoma (MCL). Recently, we demonstrated preferential DNA methylation of HOX genes in MCL compared with chronic lymphocytic leukemia (CLL), despite these genes not being expressed in either entity. Since EZH2 has been shown to regulate HOX gene expression, to gain further insight into its possible role in differential silencing of HOX genes in MCL vs. CLL, we performed detailed epigenetic characterization using representative cell lines and primary samples. We observed significant overexpression of EZH2 in MCL vs. CLL. Chromatin immune precipitation (ChIP) assays revealed that EZH2 catalyzed repressive H3 lysine 27 trimethylation (H3K27me3), which was sufficient to silence HOX genes in CLL, whereas in MCL H3K27me3 is accompanied by DNA methylation for a more stable repression. More importantly, hypermethylation of the HOX genes in MCL resulted from EZH2 overexpression and subsequent recruitment of the DNA methylation machinery onto HOX gene promoters. The importance of EZH2 upregulation in this process was further underscored by siRNA transfection and EZH2 inhibitor experiments. Altogether, these observations implicate EZH2 in the long-term silencing of HOX genes in MCL, and allude to its potential as a therapeutic target with clinical impact.