Angulate Lysosomes

Under many circumstances, macrophages accumulate lipids (possibly in combination with other materials) in the form of micelles that by their rigidity and size impart an irregular, angulate shape to the lysosomes in which they are stored. When macrophages contain large numbers of these angulate lysosomes, they have a characteristic light microscopic appearance and are often designated Gaucher cells or Gaucher-like cells. In most instances, however, the angulate lysosomes are small in number or size and are not easily recognized by light microscopy.

A search of the literature and our own files revealed angulate lysosomes in a considerable number of conditions in which they have not previously been observed or recognized. In most conditions, the evidence indicates that the material stored is derived from phagocytosed cells that are incompletely digested, either because they are simply too numerous to be handled by the macrophage or due to a primary metabolic deficiency, or both. In contrast to what has been assumed, angulate lysosomes not only arise in situations in which blood cells are phagocytosed, but also when various types of degenerating tumor cells, remnants of myelin sheaths, or bacteria accumulate inside macrophages. In yet other conditions, the origin of the lysosomal contents remains to be elucidated.     

Ultrastructure of the Liver in the Cerebrohepatorenal Syndrome of Zellweger

Three infants with clinical and biochemical features of Zellweger's cerebrohepatorenal syndrome are presented, and the ultrastructural features of successive biopsy and autopsy liver specimens are described. No hepatocellular peroxisomes were found in these patients on routine electron microscopy or electron microscopic histochemistry. In a control group of liver biopsies from 9 patients with other pediatric liver diseases, peroxisomes were readily identifiable in each hepatocyte. Apart from the absence of peroxisomes, the hepatocytes had a remarkably “normal” aspect, even in the final stages of the disease. Mitochondrial abnormalities, which have been the subject of some controversy in this syndrome, were a highly variable and inconstant finding in our cases.

We draw attention to another ultrastructural feature of the syndrome, namely the occurrence of large angulate lysosomes, containing conspicuous double lamellae, inside macrophages, which were especially abundant in later stages of the disease. These angulate lysosomes may be of additional value in the ultrastructural diagnosis of Zellweger's syndrome, especially when only poorly preserved liver tissue (e.g., paraffin-embedded or postmortem material) is available, and the absence of peroxisomes is difficult to assess. In these instances, the angulate lysosomes can still be identified with ease.     

上颌前牙区非埋入式种植体不同角度基台的三维有限元分析

背景：研究发现,在上颌前牙区的角度基台增加到25°时,种植体应力增加18%,当种植体的应力增大到其所能承受的范围之外时必然会导致种植失败率的增加,因此角度基台角度肯定不是越大越好。那么到底使用最大多少角度的角度基台不会影响种植的成功率呢？以往的研究并未给予明确的答案。 目的：观察上颌前牙区种植体连接不同角度基台时的应力应变情况,分析种植体的安全系数,确定上颌种植时能用的基台角度。 方法：通过建立三维模型,利用有限元软件计算种植体连接不同角度的角度基台时,种植体及周围骨质的应力分布。 结果与结论：种植体连接不同角度基台时,随基台角度的增大,种植体的最大von-mises应力值逐渐增大,受力部位逐渐向种植体颈部转移,各模型组相互比较,差异具有显著性意义(P < 0.05)。提示上颌前牙区种植为了远期成功率建议最大不要超过25°的角度基台;使用大于25°角度基台时应适当减少其所受牙合力。     

Ultrastructure of the Liver in the Cerebrohepatorenal Syndrome of Zellweger

Three infants with clinical and biochemical features of Zellweger's cerebrohepatorenal syndrome are presented, and the ultrastructural features of successive biopsy and autopsy liver specimens are described. No hepatocellular peroxisomes were found in these patients on routine electron microscopy or electron microscopic histochemistry. In a control group of liver biopsies from 9 patients with other pediatric liver diseases, peroxisomes were readily identifiable in each hepatocyte. Apart from the absence of peroxisomes, the hepatocytes had a remarkably “normal” aspect, even in the final stages of the disease. Mitochondrial abnormalities, which have been the subject of some controversy in this syndrome, were a highly variable and inconstant finding in our cases.

We draw attention to another ultrastructural feature of the syndrome, namely the occurrence of large angulate lysosomes, containing conspicuous double lamellae, inside macrophages, which were especially abundant in later stages of the disease. These angulate lysosomes may be of additional value in the ultrastructural diagnosis of Zellweger's syndrome, especially when only poorly preserved liver tissue (e.g., paraffin-embedded or postmortem material) is available, and the absence of peroxisomes is difficult to assess. In these instances, the angulate lysosomes can still be identified with ease.     

Identification of regions of the Beet mild curly top virus (family Geminiviridae) capsid protein involved in systemic infection, virion formation and leafhopper transmission

Plant viruses in the genus Curtovirus (family Geminiviridae) are vectored by the beet leafhopper (Circulifer tenellus) and cause curly top disease in a wide range of dicotyledonous plants. An infectious clone of an isolate of Beet mild curly top virus (BMCTV-[W4]), associated with an outbreak of curly top in pepper and tomato crops, was characterized and used to investigate the role of the capsid protein (CP) in viral biology and pathogenesis. Frameshift mutations were introduced into the overlapping CP and V2 genes, and a series of CP alanine scanning mutations were generated. All mutants replicated in tobacco protoplasts or systemically infected plants, consistent with these gene products not being required for viral DNA replication. The CP frameshift mutant and most C-terminal alanine scanning mutants did not systemically infect Nicotiana benthamiana plants or form detectable virions, and were not leafhopper-transmitted. In contrast, most N-terminal alanine scanning mutants systemically infected N. benthamiana and induced disease symptoms, formed virions and were leafhopper-transmissible; thus, these substitution mutations did not significantly alter the functional properties of this region. One N-terminal mutant (CP49-51) systemically infected N. benthamiana, but did not form detectable virions; whereas another (CP25-28) systemically infected N. benthamiana and formed virions, but was not insect-transmissible. These mutants may reveal regions involved in virus movement through the plant and/or leafhopper vector. Together, these results indicate an important role for virions in systemic infection (long-distance movement) and insect transmission, and strongly suggest that virions are the form in which BMCTV moves, long distance, in the phloem.     

Plant-feeding insects harbor double-stranded RNA viruses encoding a novel proline-alanine rich protein and a polymerase distantly related to that of fungal viruses

Novel double-stranded RNAs (∼ 8 kbp) were isolated from threecornered alfalfa hopper (Spissistilus festinus) and beet leafhopper (Circulifer tenellus), two plant-feeding hemipteran insect pests. The two new viruses, designated Spissistilus festinus virus 1 (SpFV1) and Circulifer tenellus virus 1 (CiTV1), do not appear to be encapsidated in conventional virions and shared a genome organization similar to that of several unclassified fungal viruses. SpFV1 and CiTVl encode a proline-alanine rich protein (PArp) and an RNA-directed RNA polymerase (RdRp). Expression of the 3’-proximal RdRp ORF appears to result from -1 translational frameshifting of the PArp ORF. Phylogenetic analysis of the RdRp indicated that SpFV1 and CiTV1 were most closely related to each other and the unclassified plant virus Cucurbit yellows associated virus, and more distantly related to the unclassified fungal dsRNA viruses Phlebiopsis gigantea virus 2 and Fusarium graminearum virus 3.     

Importance of Annulate Bodies in the Diagnosis of Granular Cell Tumors (Schwannomas)

Granular cell tumors (GCTs) were originally characterized ultrastructurally by the presence of many large lysosomes and angulate bodies (ABs). ABs appear to have been forgotten, and the diagnosis of GCT currently depends solely upon the presence of large lysosomes. Most investigators favor a Schwann cell origin for GCT. Recently, reports of granular tumors with large lysosomes but without ABs have suggested other cells of origin. If the ultrastructural criteria for the diagnosis of GCT were maintained as originally described, many of these granular tumors would not qualify as true GCTs. Two granular tumors that were at first considered GCTs are described. Based on the presence of large lysosomes and the presence or absence of ABs, one tumor was considered a true malignant GCT and the other a benign fibroblastic tumor.     

Contrasting effects of sewage sludge and commercial fertilizer on egg to adult development of two herbivorous insect species

Municipal sewage sludge containing heavy metals had a toxic effect on the development of the cabbage looper, Trichoplusia ni (Lepidoptera: Noctuidae), one of two herbivorous insects commonly found in an Ohio old-field which had been subjected to long-term sewage sludge application. Soils were removed in 1992 from an old-field following 11 years of heavy nutrient enrichment (1978 to 1988) with applications of either sewage sludge (Milorganite^®) containing heavy metal contaminants or urea-phosphate fertilizer. Egg to adult development rate and survival of the blackfaced leafhopper, Graminella nigrifrons (Homoptera: Cicadellidae), and the cabbage looper was determined on maize (leafhopper) and broccoli (looper) seedlings grown in soils from sludge-treated, fertilizer-treated, or untreated control plots of the old-field. Fertilizer and sludgetreated soils had higher levels of N. P and organic matter, and a lower pH than the untreated control soils, while sludge-treated soils contained significantly higher concentrations of Cd, Cu, Pb, and Zn. Maize appeared to be unaffected by the three soil treatments, and survival and rate of egg to adult development of the leafhopper was not affected. Broccoli seedlings grown in both the high nutrient fertilizer and sludge soils were greener and larger than broccoli grown in control soils. However, the cabbage looper had significant larval and pupal mortality (25 to 40%) and prolonged egg to adult development on sludge-grown broccoli compared to control and fertilizer treatments. As assimilation into the food chain of heavy metals and other organic pollutants, such as PCBs, is in part a function of the interaction of soil chemistry and type of plant, the application of municipal sludges to old-fields needs to be carefully monitored, as contaminants may have significant developmental and behavioural effects on some secondary links in the old-field food chain.     

Angulate Lysosomes

Under many circumstances, macrophages accumulate lipids (possibly in combination with other materials) in the form of micelles that by their rigidity and size impart an irregular, angulate shape to the lysosomes in which they are stored. When macrophages contain large numbers of these angulate lysosomes, they have a characteristic light microscopic appearance and are often designated Gaucher cells or Gaucher-like cells. In most instances, however, the angulate lysosomes are small in number or size and are not easily recognized by light microscopy.

A search of the literature and our own files revealed angulate lysosomes in a considerable number of conditions in which they have not previously been observed or recognized. In most conditions, the evidence indicates that the material stored is derived from phagocytosed cells that are incompletely digested, either because they are simply too numerous to be handled by the macrophage or due to a primary metabolic deficiency, or both. In contrast to what has been assumed, angulate lysosomes not only arise in situations in which blood cells are phagocytosed, but also when various types of degenerating tumor cells, remnants of myelin sheaths, or bacteria accumulate inside macrophages. In yet other conditions, the origin of the lysosomal contents remains to be elucidated.     

Reovirus genomes from plant-feeding insects represent a newly discovered lineage within the family Reoviridae

A complex set of double-stranded RNAs (dsRNAs) was isolated from threecornered alfalfa hopper (Spissistilus festinus), a plant-feeding hemipteran pest. A subset of these dsRNAs constitute the genome of a new reovirus, provisionally designated Spissistilus festinus reovirus (SpFRV). SpFRV was present in threecornered alfalfa hopper populations in the San Joaquin Valley of California, with incidence ranging from 10% to 60% in 24 of 25 sample sets analyzed. The 10 dsRNA segments of SpFRV were completely sequenced and shown to share conserved terminal sequences (5′-AGAGA and CGAUGUUGU-3′) of the positive-sense strand that are distinct from known species of the family Reoviridae. Comparisons of the RNA directed RNA polymerase (RdRp) indicated SpFRV is most closely related (39.1% amino acid identity) to another new reovirus infecting the angulate leafhopper (Acinopterus angulatus) and provisionally designated Acinopterus angulatus reovirus (AcARV). The RdRp of both viruses was distantly related to Raspberry latent virus RdRp at 27.0% (SpFRV) and 30.0% (AcARV) or Rice ragged stunt virus RdRp at 26.2% (SpFRV) and 29.0% (AcARV) amino acid identity. RdRp phylogeny confirmed that SpFRV and AcARV are sister taxa sharing a most recent common ancestor. SpFRV segment 6 encodes a protein containing two NTP binding motifs that are conserved in homologs of reoviruses in the subfamily Spinareovirinae. The protein encoded by SpFRV segment 4 was identified as a guanylyltransferase homolog. SpFRV segments 1, 3, and 10 encode homologs of reovirus structural proteins. No homologs were identified for proteins encoded by SpFRV segments 5, 7, 8, and 9. Collectively, the low level of sequence identity with other reoviruses, similar segment terminal sequences, RdRp phylogeny, and host taxa indicate that SpFRV and AcARV may be considered members of a proposed new genus of the family Reoviridae (subfamily Spinareovirinae), with SpFRV assigned as the type species.