Pancreatic islet cytology of ictaluridae (Teleostei)

Summary The endocrine pancreas of the bullhead catfish, Ictalurus nebulosus, and the channel catfish, I. punctatas was studied by light and electron microscopy. In addition to the usual A, B and D cells, a fourth endocrine cell type was consistently observed in the electron microscope. All endocrine cell types were innervated. The vesicles of most of the nerve endings were ultrastructurally different from typical adrenergic and cholinergic vesicles, strongly suggesting the possibility of a third autonomic neurotransmitter serving as a regulator of catfish islet secretion.Supported in part by PHS grant AM 11407 awarded to Dr. Bryce Munger.     

Ultrastructure of the grasshopper proximal femoral chordotonal organ

Summary Calpasoma dactyloptera, a tentacled form of minute, freshwater coelenterate, has been investigated by light and electron microscopy and time-lapse cinematography. Each tentacle consists of a protrusion from a single ectodermal epithelial cell termed a tentaculocyte. hin tentaculocyte vesicles which represent invaginations of the plasma membrane. A cnidocil protrudes into the external medium. The bottom of each nematocyte is elongated as a stalk which extends to the tentacle base, coursing through tubular membrane lined channels within the tentaculocyte. A network of fibers and microtubules, originating in the cnidocil, extends to the base of the nematocyte stalk.Supported by PHS Research Career Development Award 1-K04-GM42595 and NSF Research Grant GB 29284.     

Substance P and acetylcholine are co-localized in the pathway mediating mucociliary activity in Rana pipiens

Mucociliary activity is an important clearance mechanism in the respiratory system of air breathing vertebrates. Substance P (SP) and acetylcholine play a key role in the stimulation of the mucociliary transport in the frog palate. In this study, retrograde neuronal tracing was combined with immunocytochemistry for SP and choline acetyl transferase (ChAT) in the trigeminal ganglion and for neurokinin-1 receptor (NK1R) in the palate of Rana pipiens. The cells of origin of the palatine nerve were identified in the trigeminal ganglion using the retrograde tracer Fluorogold (FG). Optimal labeling of FG cells in the trigeminal ganglion was obtained at 96 h of exposure. Immunoflorescent shows that SP and acetylcholine are co-localized in 92% of the cells labeled with FG in the trigeminal ganglion. NK1 receptors were found in the membrane of epithelial and goblet cells of the palate. Ultrastructural study of the palate showed axonal-like endings with vesicles in connection with epithelial and goblet cells. These results further support the concerted action of both neurotransmitters in the regulation of mucociliary activity in the frog palate.     

Achieving Molecular Selectivity in Imaging Using Multiphoton Raman Spectroscopy Techniques

In the case of most optical imaging methods, contrast is generated either by physical properties of the sample (Differential Image Contrast, Phase Contrast), or by fluorescent labels that are localized to a particular protein or organelle. Standard Raman and infrared methods for obtaining images are based upon the intrinsic vibrational properties of molecules, and thus obviate the need for attached fluorophores. Unfortunately, they have significant limitations for live-cell imaging. However, an active Raman method, called Coherent Anti-Stokes Raman Scattering (CARS), is well suited for microscopy, and provides a new means for imaging specific molecules. Vibrational imaging techniques, such as CARS, avoid problems associated with photobleaching and photo-induced toxicity often associated with the use of fluorescent labels with live cells. Because the laser configuration needed to implement CARS technology is similar to that used in other multiphoton microscopy methods, such as two-photon fluorescence and harmonic generation, it is possible to combine imaging modalities, thus generating simultaneous CARS and fluorescence images. A particularly powerful aspect of CARS microscopy is its ability to selectively image deuterated compounds, thus allowing the visualization of molecules, such as lipids, that are chemically indistinguishable from the native species.     

Transport of Endocytosed Material Into Melanin Granules in Cultured Choroidal Melanocytes of Cattle—New Insights Into the Relationship of Melanosomes With Lysosomes

Cultured choroidal melanocytes from cattle were incubated with gold labeled albumin. After phagocytosis of the labeled protein, the label appeared inside the melanin granules, as was observed under the electron microscope. Melanin granules associated with gold particles were also exocytosed into the culture medium by the melanocytes. The results of this study show that endosomes or phagosomes are transported from the cell surface of a melanocyte to the melanin granules. Therefore, melanin granules are part of the lysosomal degradation pathway. The possibility that albumin is degraded by proteases present in lysosomes and melanosomes and that the tyrosine released during degradation is used as substrate by tyrosinase and thereby converted to melanin is discussed. The present study additionally shows that the choroidea of cattle can be used as a source for cell culture of melanocytes.     

EFFECTS OF DISTURBANCE ON EPIPHYTIC COMMUNITY ARCHITECTURE1

Microdistributional patterns of attached algal communities on Cladophora and glass slides were compared under varying disturbance regimes in the Upper Mississippi River, using light and scanning electron microscopy. Localized physical disturbance, induced by boat traffic and wind-generated wave action in the main channel, inhibited development of complex attached algal communities and maintained an adnate flora with two-dimensional architecture. In contrast, communities protected from disturbance developed a more complex, three-dimensional architecture. A high degree of architectural similarity was observed between communities on Cladophora and glass substrates exposed to similar levels of disturbance. Communities exposed to severe disturbance resembled ones in early stages of colonization and development, whereas less disturbed communities were similar to ones in advanced stages of development. These results demonstrated that turbulence strongly influences the community structure of periphyton on both micro and macro scale levels.     

中国大鲵视网膜的光镜和扫描电镜研究

用光镜和扫描电镜观察了大鲵视网膜各类细胞的形态及分布, 对视细胞和节细胞进行计数。视网腊中三个核层及两个网状层分布均匀,无中央凹。每张视网膜的视细胞总数约130000,节细胞约8000,视杆与视锥之比为8.5：1。扫描电镜下,视杆外节表面的小叶间沟清晰;视杆视锥外节均有从内节伸出的20-30条萼状突起;核周体表面亦有20-30条细胞质突起。文中还报道了幼体视细胞的形态及密度。讨论了上述结构的机能。     

Perfectly registered multiphoton and reflectance confocal video rate imaging of in vivo human skin

We present a multimodal in vivo skin imaging instrument that is capable of simultaneously acquiring multiphoton and reflectance confocal images at up to 27 frames per second with 256 × 256 pixel resolution without the use of exogenous contrast agents. A single femtosecond laser excitation source is used for all channels ensuring perfect image registration between the two‐photon fluorescence (TPF), second harmonic generation (SHG), and reflectance confocal microscopy (RCM) images. Images and videos acquired with the system show that the three imaging channels provide complementary information in in vivo human skin measurements. In the epidermis, cell boundaries are clearly seen in the RCM channel, while cytoplasm is better seen in the TPF imaging channel, whereas in the dermis, SHG and TPF channels show collagen bundles and elastin fibers, respectively. The demonstrated fast imaging speed and multimodal imaging capabilities of this MPM/RCM instrument are essential features for future clinical application of this technique. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

The Association of Phytoplasma with Stunting, Leaf Necrosis and Witches' Broom Symptoms in Magnolia Plants

In 1999–2000 a severe disease was observed on plants of four Magnolia spp. cultivated in a commercial nursery in Poland. Affected plants showed a progressive loss of vigour, were stunted, and had severely malformed leaves, leaf necrosis and witches' broom. Phytoplasma was detected in magnolias with severe symptoms and in dodder-inoculated Catharanthus roseus seedlings by nested polymerase chain reaction (PCR) assay with primer pair R16F1/R0 followed by universal (rA/fA) and group specific (R16(I)F1/R1) primer pairs which amplified a fragment of phytoplasma 16S rDNA. The PCR products (560 bp or 1.1 kb) of all samples used for restriction fragment length polymorphism analysis after digestion with endonuclease enzymes Alu I and Mse I produced the same profile which corresponded to that of an aster yellows phytoplasma reference strain. Phytoplasma DNA was detected throughout the growing season in roots, stems and young but not mature leaves. Electron microscope examination of the ultra-thin sections of the leaf and stem of diseased magnolias showed collapsed and degenerated sieve tube elements with wall thickening. The reduced lumen of these sieve elements contained numerous vesicles and membrane-bound structures, but no typical phytoplasma cells. This is the first report of aster yellows phytoplasma in magnolia identified by molecular assays.