Secretory Patterns in Colleters of Apocynaceae

Colleters of Apocynaceae are glands related to different types of protection of vegetative and floral meristems through the production of mucilage or a mixture of many different compounds. Although several anatomical papers have shown histological and histochemical aspects of colleters of the family, almost nothing is known about their secretory process. In this study, we analyzed two types of colleters in Apocynaceae: one produces mucilage and lipophilic compounds, while the other produces an exclusively mucilaginous secretion. The secretory epidermis of the colleters of Allamanda schottii and Blepharodon bicuspidatum has a dense cytoplasm with organelles responsible for the production of mucilage and lipids. This heterogeneous secretion is released through granulocrine and eccrine mechanisms and is temporarily stored in a subcuticular space before crossing the cuticle. Conversely, colleters of Mandevilla splendens and Peplonia axillaris produce only mucilage and have a very different secretory apparatus. The mechanism of secretion is granulocrine, and the exudate is firstly accumulated in a large periplasmic space and later in an intramural space before crossing the cuticle. Notably, the structure of the cuticle varies according to the secretion composition. Although the colleters of the family are histologically similar, this study demonstrates a metabolic and subcellular variability previously unknown for Apocynaceae.

Morphological and p40 immunohistochemical analysis of squamous differentiation in endoscopic ultrasound guided fine needle biopsies of pancreatic ductal adenocarcinoma

The basal-like molecular subtype of pancreatic ductal adenocarcinoma (PDAC) is associated with poor prognosis and upregulation in TP63ΔN (p40) network. Adenosquamous histology can be observed. This study assessed immunohistochemical p40 expression in fine needle biopsy (FNB) samples with PDAC and association with cytomorphological features of squamous differentiation and clinical data. 106 EUS FNBs with PDAC were assessed for eight cytomorphological features of squamous differentiation. P40 H-score (intensity 0–3 × percentage positive nuclei) was analysed for association with morphological features, patient age, gender, operability, chemotherapy and survival. P40 H-score in 14 paired FNBs and resections was compared. P40 h-score was 1–3 in 31%, 4–30 in 16% and > 30 in 13% of FNBs. It was significantly associated with intercellular bridges, elongated cell shape, sharp cell borders, angular nuclei with homogenous chromatin (p < 0.001) and dense cytoplasm (p = 0.002). Keratinisation was not seen. Inoperable patients (n = 81) had a shorter median survival for h-score > 30 (n = 9, 1.8 months) than for h-score ≤ 30 (n = 66, 6.7 months) not quite reaching statistical significance (p = 0.08). P40 was significantly associated with squamous morphology in FNBs with PDAC. P40 H-score > 30 showed a trend towards shorter survival in inoperable patients. Squamous differentiation may be a treatment target in PDAC.

Morphological, biochemical and molecular hallmarks of programmed cell death in stigmatic papillae of Brassica oleracea L.

The aim of this study is to determine the programmed cell death hallmarks in the stigmatic papillae of Brassica oleracea L. The flower development was divided in two main stages; pre-anthesis and post-anthesis. Programmed cell death hallmarks were examined in parallel to these stages. At pre-anthesis, the stigmatic papillae were ovoid and their dense cytoplasm were rich in insoluble polysaccharide and protein. At post-anthesis, vacuolization and enlargement were quite evident in papillae. Besides, the protein content decreased, but reactive oxygen species increased in comparison to the pre-anthesis stage. Although no significant change in superoxide dismutase activity was detected, catalase activity decreased and hydrogen peroxide content increased at post-anthesis. DAPI stained nuclei appeared rounded and smooth appearance at pre-anthesis, however, some invaginations and fragmentation in nuclei were observed at post-anthesis. Although, TUNEL staining was negative at pre-anthesis, while TUNEL positive reaction was significant in the nuclei of papillae at post-anthesis. In comparison to the pre-anthesis, the number of fragmented nuclei monitored by DAPI and TUNEL staining increased at post-anthesis.

The relationship between morphology changes and antioxidant enzymes activity during somatic embryogenesis of long-term-maintained callus of Zoysia matrella [L.] Merr.

A callus line of manila grass (Zoysia matrella [L.] Merr.) has been maintained for 8 years in our lab. The present study investigated changes in ultrastructure and antioxidant enzyme activity during regeneration of the callus and examined the correlation between these changes and regeneration ability. The changes in fresh weight and diameter of the callus over time could be described by a sigmoidal growth curve with different stages. Electron microscopy revealed small embryonic callus cells, isodiametric in shape, with large, obvious nuclei and dense cytoplasm. The cellular structures and morphology changed dramatically as regeneration proceeded. Of particular note was the formation of folded scutellum-like embryos at 14 d, which might be the turning point for morphological differentiation. Catalase (CAT) and peroxidase (POD) activities were the lowest at 14 d, the same time when superoxide dismutase (SOD) activity was the highest. Thus, we speculate that the formation of the scutellum-like structures is associated with higher activity of SOD and lower activities of CAT and POD.

More than Scales: Evidence for the Production and Exudation of Mucilage by the Peltate Trichomes of Tillandsia cyanea (Bromeliaceae: Tillandsioideae)

Bromeliad scales have been investigated extensively due to their recognition as a key ecological and evolutionary feature of Bromeliaceae. However, much remains unknown about such trichomes and only recently mucilage exudation was described for them in a species of the subfamily Bromelioideae. The present study aimed to investigate the secretion present in inflorescences of Tillandsia cyanea Linden ex K. Koch (Tillandsioideae) to determine whether the scales of this species also produce and release secretions. Samples of young and mature portions of inflorescences were collected and prepared according to standard methods for light and electron microscopy. Anatomical and ultrastructural results indicate that the secretion is produced by the wing portion of typical peltate trichomes on the adaxial surface of bracts. The secretory activity begins in the early stages of trichome expansion and characteristically occurs in cells exhibiting a porous cuticle and dense cytoplasm with numerous mitochondria and dictyosomes. Histochemical tests confirmed mucilage secretion and revealed proteins in the exudate. These data comprise the first record of mucilage exudation by trichomes within Tillandsioideae and indicate that this capacity may be more relevant to bromeliad biology than previously considered. Functional aspects and colleter-like activity are also discussed.

Revisiting the histological patterns of storage tissues: beyond the limits of gall-inducing taxa

Gall-inducing Aphididae may feed directly on phloem, whereas Eriophyidae and Nematoda feed on cells lining the gall chambers. We assume that a variation in structural complexity will occur within galls induced by each taxon, and that the complexity of the galls could be related to the types of storage tissue they have. Histological, histometric, and histochemical analyses were used to compare six gall systems with different levels of complexity. Such levels are not taxon-related, even though eriophyid galls are usually simpler than nematode and aphid galls. The histological features of galls allowed the classification of storage tissues into three types: typical nutritive tissues (TNT), common storage tissues (CST), and nutritive-like tissues (NLT). The TNT and NLT have cells with dense cytoplasm and a prominent nucleus. The CST cells are vacuolated, and may store starch and other energy-rich molecules, as do the NLT cells. In contrast to NLT or CST, the TNT serves as a direct food source for gall inducers, and it is present in nematode and some eriophyid galls. NLTs may be present in some aphid galls, but are not the direct feeding site. The CST occurs on galls of all three inducing taxa.

Embryo sac haustorium in Dryas octopetala L. (Rosaceae)

The embryo sac haustorium found in <em>Dryas octopetala</em> L. from the Tatra Mts is the first record of its occurrence in <em>Rosaceae</em>. At the eight-nucleate stage of the embryo sac, the antipodal end of the central cell began to grow into a narrow caecum filled with dense cytoplasm and elongated in the chalazal direction leaving the three antipodals in situ. The haustorium enlarged and lost its characteristic shape after the period of fertilization. Finally, the embryo sac occupied almost the whole length of the ovule. Situated at its chalazal end there was either dense cytoplasm with a group of endosperm nuclei or dense, grainy cytoplasm only, if fertilization had not taken place.

Activation of rape (Brassica napus L.) embryo during seed germination. III. Ultrastructure of dry embryo axis

Mature dry winter rape (<em>Brassica napus</em> L.), var. <em>oleifera</em>, cv. Górczański embryos were studied in the light and the electron microscope. Considerable modifications and regression of the cell ultrastructure were noted in the resting embryo as compared with the metabolically active cells. The degree of regression of the ultrastructure differed in the particular organs and tissues of the embryo. Of most regressed character are the cells of the storage organs - the hypocotyl and cotyledones. They are almost completely filled with protein and lipid bodies. The small spaces between them are filled with dense cytoplasm with a lobular nucleus and not numerous, difficult to identify, plastids and mitochondria. The cells of the shoot primordium and radicle, particularly of the protoderm at the boundary of the hypocotyl and root and columella of root cap have a less regressed ultrastructure. They contain less storage material, a less dense cytoplasm and nearly all cell organelles with a normal appearance. The mitochondria are quite numerous with rather large cristae. Plastids are large with characteristic infolds filled with cytoplasm and some lamellae and a few agglomerations of plastoglobules. The nucleus is lobular with distinctly double and porous nuclear envelope and uniformly dense nucleolus. These cells do not contain dictyosomes and the ER is reduced to short, mostly rough cisternae and vesicles. Cells within the columella itself are also differentiated. The least regression of ultrastructure is seen in the cells of external layers containing the most numerous and most active looking mitochondria and more ER structures. The promeristem cells are similar to those of the deeper columella layers but their mitochondria are more regressed. The cells of the lateral parts of the cap and radicle cells, distant from the promeristem are more similar to the hypocotyl cells.

Pollen dimorphism and androgenesis in Hordeum vulgare

Dimorphism of binucleate pollen grains of <em>Hordeum vulgare</em> has been confirmed. It is considered, however, in contrast to the accepted opinions, that some of the large pollen grains with dense cytoplasm lying close to the tapetum are the outset forms for embryoids, and not the small pollen grains with scarce cytoplasm lying in the pollen sac centre.

Structure of the extrafloral nectaries of Vicia (L.) Fabaceae

Extrafloral nectaries on the abaxial surface of stipules were investigated in the <i>Vicia angustifolia, Vicia sativa, Vicia sepium</i> and <i>Vicia grandiflora</i>. In V. <i>angustifolia</i> nectaries were also located on the calyx surface. Nectaries were consisted of secretory hairs and 2-31ayers of subepidermal cells. Secretory hair was built of four cells of head, one stalk cell and basal cell. Head cells showed character of transfer cells because of walls ingrowths and dense cytoplasm with numerous mitochondria.