Apoptotic wing degeneration and formation of an altruism-regulating glandular appendage (gemma) in the ponerine ant <Emphasis Type="Italic">Diacamma</Emphasis> sp. from Japan (Hymenoptera,Formicidae, Ponerinae)

We here show an example of morphological novelties, which have evolved from insect wings into the specific structures controlling social behaviour in an ant species. Most ant colonies consist of winged queen(s) and wingless workers. In the queenless ponerine ant Diacamma sp. from Japan, however, all female workers have a pair of small thoracic appendages, called gemmae, which are homologous to the forewings and acts as an organ regulating altruism expression. Most workers, whose gemmae are clipped off by other colony members, become nonreproductive helpers, while only a single individual with complete gemmae becomes functionally reproductive. We examined histologically the development of gemmae, and compared it with that of functional wings in males. Female larvae had well-developed wing discs for both fore- and hindwings. At pupation, however, the wing discs started to evaginate and later degenerate. The hindwing discs completely degenerated, while the degeneration of forewing discs was incomplete, leading to the formation of gemmae. The degeneration process involved apoptotic cell death as confirmed by TUNEL assay. In addition, glandular cells differentiated from the epithelial cells of the forewing buds after completion of pupation. The mechanism of developmental transition from wing to gemma can be regarded as an evolutionary gain of new function, which can be seen in insect appendages and vertebrate limbs.Edited by P. Simpson     

Ultrastructural ontogeny of leaf cavity trichomes inAzolla implies a functional role in metabolite exchange

Summary Anabaena azollae is associated with two types of multicellular epidermal trichomes inAzolla leaf cavities, the simple and branched hairs. The observation of transfer cell ultrastructure in some hair cells led to speculation that the cavity hairs might participate in metabolite exchange between the symbionts. The developmental ontogeny of cavity trichomes is described here, using transmission electron microscopy, with a goal of improving our understanding of possible functions of these structures in the symbiosis. The observations have established that all cells of simple and branched hairs develop the structural characteristics of transfer cells, but not simultaneously. Rather, there is an acropetal succession of transfer cell ultrastructure beginning in terminal cells, moving to body cells where present, and ending in stalk cells. The transfer cell stage is followed immediately by senescence in all hair cells. The timing of transfer cell differentiation, considered together with information from other studies, suggests that branched hairs may be involved in exchange of fixed nitrogen between the symbionts, while simple hairs may participate in exchange of fixed carbon fromAzolla toAnabaena. Contribution no. 869 from the Battelle-C. F. Kettering Research Laboratory.     

The pineal gland of the mole (Talpa europaea L.)

Summary The ultrastructure of the mole pinealocytes, a mammal which lives practically in complete darkness, has been examined and compared with that of other mammals. Mitochondria, ribosomes, smooth and granular endoplasmic reticulum, lysosomes and lipid incluclusions are present in the perikaryon. The presence of a paracrystalline structure of a possibly proteinaceous nature in some cisterns of the granular endoplasmic reticulum and between the two layers of the nuclear membrane, is characteristic of the mole pinealocyte. The Golgi complex produces clear vesicles of 500–1500 Å in diameter. Occasionally, some dense core secretory vesicles were observed in the perikaryon and in the ending of cell processes. Their presumed origin from the Golgi complex could not yet be demonstrated. A large number of ciliary derivatives (9+0 pattern) are also present in the mole pinealocyte.

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Résumé Les pinéalocytes (au sens strict: Wolfe, 1965) de l'épiphyse de la Taupe (animal vivant pratiquement toujours dans une complète obscurité) examinés au microscope électronique, ont été comparés à ceux d'autres Mammifères. Dans le périkaryon des mitochondries, des ribosomes, du réticulum endoplasmique lisse et granulaire et quelques lysosomes et inclusions lipidiques sont présents. La présence à l'intérieur de certaines cavités du réticulum endoplasmique granulaire et parfois entre les deux feuillets de l'enveloppe nucléaire, de structures paracristallines (de nature protéique ?) est caractéristique des pinéalocytes de cet animal. L'appareil de Golgi sécréte des vésicules claires de 500 à 1500 Å de diamètre. Quelques très rares grains de sécrétion, dont l'origine golgienne n'a pas encore été démontré, ont été observé dans le périkaryon et à l'extrémité de certains prolongements. Un grand nombre de structures ciliaires (9+0 paires de tubules) ont également été observés dans les pinéalocytes.

     

Ontogeny of external glands in the bladderwortUtricularia monanthos

Summary The development of external glands on traps and stolons ofU. monanthos has been studied using transmission electron microscopy. During early differentiation of the epidermis some cells remain narrow and develop a protuberance which subsequently divides into a terminal and a pedestal cell, with the remainder of the original cell forming the basal epidermal cell of the gland. The lateral wall of the pedestal cell soon becomes densely impregnated throughout its thickness, and this is followed by the formation of discontinuous cuticular deposits within the primary wall of the terminal cell. The outer wall of the terminal cell then usually undergoes extensive secondary wall thickening beginning with the formation of ingrowths which for a period characterize the cell as a transfer cell. Later, at the stage when traps begin capturing prey, these ingrowths are overlain by further layers of secondary wall material. Concomitantly, in the pedestal cell, wall ingrowths become fully differentiated on the outer transverse wall and persist throughout the remaining life of the gland.The function of external glands during early ontogeny is discussed. At the stage when the terminal cell is differentiated as a transfer cell it is suggested that the gland is mainly responsible for absorbing solutes from the external medium. Once traps commence capturing prey the gland may become modified for a rôle in water secretion, facilitated by the differentiation of the pedestal cell as a transfer cell, and by the formation of a thick outer wall in the terminal cell.     

鸡新城疫副眼和副鼻器官微环境局部免疫机理的研究——Ⅱ.免疫组织学和电镜研究

本文研究了以点眼和滴鼻途径接种了新城疫 B_1系疫苗后的不同时期 SPF 雏鸡的哈德泪腺、气管、肺脏、脾脏、胸腺和法氏囊的免疫组织学及其在电子显微镜下的变化规律。证明在哈德泪腺的腺导管、腺泡间质、气管粘膜的固有层和粘膜下层、肺各级支气管粘膜固有层和粘膜下层及附近肺泡壁中、肺间质中都以聚集或弥散形式存在着比对照组多的淋巴细胞,这些淋巴细胞有时形成淋巴小结样结构,还可看到较多的浆细胞。这些淋巴细胞在电子显微镜下主要表现为线粒体、粗面内质网和核糖体等细胞器增多,细胞呈旺盛的活动状态,同时哈德泪腺、气管粘膜杯状细胞和单泡腺分泌增多,气管粘膜上的纤毛也增多,这有利于将产生的抗体及时排出和防止病毒粘附。     

Cell dynamics during cocoon secretion in the aquatic leech, Theromyzon tessulatum (Annelida: Clitellata: Glossiphoniidae)

One distinguishing feature of clitellate annelids is the presence of specialized segments comprising the clitellum, whose primary function is to secrete a cocoon. Using histological analyses, we have documented cell types (I-V) and cellular processes associated with cocoon secretion in the aquatic leech, Theromyzon tessulatum. Our data indicate that the bulk of the cocoon's biomass arises from precursor cells of a single type that hypertrophy and proliferate ∼1 week prior to egg laying, and then differentiate into either of two cell types (i.e., Type II or Type III) depending on their position within the clitellum. Type II cells are concentrated along the lateral edges and venter of the clitellum and secrete alcian blue-staining granules that form opercula (i.e., glue-like material that seals both cocoon ends), while Type III cells populate the dorsal midline and secrete azocarmine-staining granules that build the cocoon wall. Both cell types occupy spaces between deep muscle layers and extend long-neck tubules to the surface epithelium as they fill with granules a few days prior to egg laying. Other cell types appear to make minor contributions to the cocoon (e.g., Type I, Type IV) or have supporting or signaling roles (e.g., Type V). Our observations suggest that post-translational modification (i.e., glycosylation) of the same core protein(s) distinguishes the granules of Type II/III cells, and that the default state of the Type II/III precursor may be evolutionarily linked to secretory cells in basal polychaetes.     

Dipetalodipin, a novel multifunctional salivary lipocalin that inhibits platelet aggregation, vasoconstriction, and angiogenesis through unique binding specificity for TXA2, PGF2alpha, and 15(S)-HETE

Dipetalodipin (DPTL) is an 18 kDa protein cloned from salivary glands of the triatomine Dipetalogaster maxima. DPTL belongs to the lipocalin superfamily and has strong sequence similarity to pallidipin, a salivary inhibitor of collagen-induced platelet aggregation. DPTL expressed in Escherichia coli was found to inhibit platelet aggregation by collagen, U-46619, or arachidonic acid without affecting aggregation induced by ADP, convulxin, PMA, and ristocetin. An assay based on incubation of DPTL with small molecules (e.g. prostanoids, leukotrienes, lipids, biogenic amines) followed by chromatography, mass spectrometry, and isothermal titration calorimetry showed that DPTL binds with high affinity to carbocyclic TXA(2), TXA(2) mimetic (U-46619), TXB(2), PGH(2) mimetic (U-51605), PGD(2,) PGJ(2), and PGF(2α). It also interacts with 15(S)-HETE, being the first lipocalin described to date to bind to a derivative of 15-lipoxygenase. Binding was not observed to other prostaglandins (e.g. PGE(1), PGE(2), 8-iso-PGF(2α), prostacyclin), leukotrienes (e.g. LTB(4), LTC(4), LTD(4), LTE(4)), HETEs (e.g. 5(S)-HETE, 12(S)-HETE, 20-HETE), lipids (e.g. arachidonic acid, PAF), and biogenic amines (e.g. ADP, serotonin, epinephrine, norepinephrine, histamine). Consistent with its binding specificity, DPTL prevents contraction of rat uterus stimulated by PGF(2α) and induces relaxation of aorta previously contracted with U-46619. Moreover, it inhibits angiogenesis mediated by 15(S)-HETE and did not enhance inhibition of collagen-induced platelet aggregation by SQ29548 (TXA(2) antagonist) and indomethacin. A 3-D model for DPTL and pallidipin is presented that indicates the presence of a conserved Arg(39) and Gln(135) in the binding pocket of both lipocalins. Results suggest that DPTL blocks platelet aggregation, vasoconstriction, and angiogenesis through binding to distinct eicosanoids involved in inflammation.     

Secretion Stimulates Intramembrane Proteolysis of a Secretory Granule Membrane Enzyme

Regulated intramembrane proteolysis, a highly conserved process employed by diverse regulatory pathways, can release soluble fragments that directly or indirectly modulate gene expression. In this study we used pharmacological tools to identify peptidylglycine α-amidating monooxygenase (PAM), a type I secretory granule membrane protein, as a γ-secretase substrate. PAM, an essential enzyme, catalyzes the final step in the synthesis of the majority of neuropeptides that control metabolic homeostasis. Mass spectroscopy was most consistent with the presence of multiple closely spaced NH₂ termini, suggesting that cleavage occurred near the middle of the PAM transmembrane domain. The luminal domains of PAM must undergo a series of prohormone convertase or α-secretase-mediated cleavages before the remaining transmembrane domain/cytosolic domain fragment can undergo a γ-secretase-like cleavage. Cleavage by γ-secretase generates a soluble fragment of the cytosolic domain (sf-CD) that is known to localize to the nucleus. Although PAM sf-CD is unstable in AtT-20 corticotroph tumor cells, it is readily detected in primary rat anterior pituitary cells. PAM isoform expression, which is tissue-specific and developmentally regulated, affects the efficiency with which sf-CD is produced. sf-CD levels are also modulated by the phosphorylation status of the cytosolic domain and by the ability of the cytosolic domain to interact with cytosolic proteins. sf-CD is produced by primary rat anterior pituitary cells in response to secretogogue, suggesting that sf-CD acts as a signaling molecule relaying information about secretion from the secretory granule to the nucleus.     

Development of serous cutaneous glands in Scinax nasica (Anura,Hylidae): patterns of poison biosynthesis and maturation in comparison with larval glands in specimens of other families

We examined the development of serous (poison) cutaneous glands in larval and juvenile Scinax nasica (Hylidae) at the ultrastructural level. We describe the biosynthesis and maturation of the cutaneous poison in comparison with the corresponding processes in representatives of Discoglossidae, Leptodactylidae, Pelobatidae and Pipidae. Serous biosynthesis in S. nasica starts in discrete adenoblasts and continues in the syncytial secretory unit. Biosynthetic processes involve rough endoplasmic reticulum and the Golgi apparatus, that releases membrane-bounded material, varying from fine grained to flocculent. During the post-Golgian secretory phase, this material undergoes initial maturation, and two products are formed: dense granules and larger vesicles holding a thin substance that will later be structured into a three-dimensional, honeycomb-like net. Both the secretory granules and vesicles change into glomerular-like aggregates of bowed, rod-shaped subunits (modules). In adult frogs, formation of dense granules is bypassed. The modular granule substructure seems to be related to the merocrine release of small amounts of poison, involved in regulating skin homeostasis. Comparison with maturational changes in larval glands of species representing four anuran families discloses similar patterns in the Leptodactylidae, but production of opaque homogeneous granules occurs in the Discoglossidae, clear vesicles in the Pelobatidae and aggregates of dense bars in the Pipidae.