Gastrointestinal neuropeptides suppress human colonic lamina propria lymphocyte DNA synthesis.

Gastrointestinal neuropeptides have been shown to modulate the circulatory immune system, but their effect on the mucosal immune system is not well defined. We studied the effect of VIP, SOM, S-P and Bomb on thymidine incorporation into human colonic lamina propria lymphocyte (LPL) DNA. Physiologic concentrations of VIP, SOM, S-P and Bomb significantly suppressed thymidine incorporation into Con A-stimulated human LPL. These neuropeptides did not affect DNA synthesis when LPL were induced with phorbol ester (PDB) and calcium ionophore (ionomycin). Our data suggest that a) VIP, SOM, S-P, and Bomb may have a regulatory role in the human mucosal immune system, and b) Bomb should be added to the list of neuropeptides which affect the gut immune system.     

Rumen fungi: morphological types from Georgia cattle and the attack on forage cell walls

Fungal colonies developing in anaerobic media from zoospores in rumen fluid from cows eating Cynodon dactylon or Medicago sativa included types showing monocentric and polycentric growth. High energy supplements added to diets of Sorghum bicolor silage increased fungal numbers in the rumen, but increases were also affected by the history and predisposition of the animal. Mixed fungal types in rumen fluid and pure cultures of isolates showing monocentric and polycentric growth degraded and weakened lignocellulosic tissues and penetrated the cuticle of C. dactylon leaf blades. By weakening or degrading recalcitrant structures in forages, rumen fungi may alter physical parameters of plants that influence utilization of fibre by ruminants.     

The second cell membrane: the basal lamina and the tissue cell theory of metazoa.

We suggest that the basal lamina is essentially a second plasma or cell membrane appearing at the next higher level of biological organization; that together with associated cell monolayers it creates a tissue level membrane which is used to form multicellular cells and that collections of these provide the essential structure of metazoa. Thus when the histological structure of multicellular organisms is viewed in a topologically simplified form such organisms appear to be sets of multicellular cells (m-cells) formed by a unit tissue membrane built around the basal lamina. Not only are m-cells in this way structurally isomorphous (homeomorphic) to unit or classical biological cells (u-cells) but the two cellular levels are also functionally isomorphous. This suggests a “General Principle of Hierarchical Isomorphism or Iteration”, i.e. that multicellular evolution recapitulates unicellular evolution. This principle of structural and functional isomorphic mappability of unicellular onto multicellular organisms then governs the organization of matter all the way from molecules to man. Just as cytoplasm precipitates the bimolecular plasma membrane to form u-cells for the purpose of achieving reaction sequestration, in turn, these u-cells precipitate a common basal lamina to form m-cells, the histologist's acini, to produce sequestered “tissue plasms”. Thus, the “generalized acinus” with its basal laminar complex seem to constitute a second level (multicellular) cell and cell membrane, respectively.Four operators, ultimately under genetic control, can generate both u and m-cells from planar configurations of their respective unit membranes therewith providing the essential structure of all cells, tissues, organs and organisms. These are the ply, permeability vector, topological and stratificational operators. They are collected into a set of “organ formulae”. Both the plasma membrane and the basal lamina act as covering membranes and, again, as membranes for subcells so that a complete multicellular organism is a tetrahierarchical cell in which the molecule is the element of the first two cellular domains and the cell is the element of the last two. The analysis identifies a new transport organ group which together with the classical endocrine and exocrine groups comprises nearly the whole of the soft tissue organs. In a major reduction, all these organs are continuously (topologically) transformable into each and into hollow spheres, cells or acini thus greatly simplifying the histology of metazoa. Given this emphasis on cellularization it would seem that life, i.e. the autonomous chemoservo, results from the cooperation of cellularization and replication operations on the catalyzation process. Through cellularization, the lipid bilayer and basal laminar membranes provide the essential catalytic reaction sequestration demanded by chemical reaction theory while through complementary base pairing the DNA double helix provides the essential memory which stores the patterns of the variations of the sequestered reactions.     

A review of insect stem cell types

Insect stem cells have been described from both embryonic and adult tissues from a diversity of insect species, although much of the focus in insect stem cell research has been on Drosophila. Insects are a vast and diverse group and it is surprising that a critical aspect of their development like stem cells has not received more attention. In this review we discuss the current state of knowledge of insect stem cell types. We examine what stem cell types have been identified from insects, and briefly discuss what is known about their regulation.     

Intrafusal fibre types in rat limb muscle spindles: morphological and histochemical characteristics.

Morphological, histochemical and ultrastructural characteristics of intrafusal fibre types were studied in rat muscle spindles. The existence of three intrafusal fibre types, namely the typical bag, the intermediate bag and the chain fibres was confirmed. Intrafusal fibres differ in diameter, length and number of nuclei in the equatorial zone. Histochemically, typical bag fibres exhibit both alkali- and acid-stable ATPase activity and low SDH activity. Intermediate bag fibres possess low alkali-stable ATPase activity; after acid-preincubation, however, they have low activity only in the juxtaequatorial region, whereas in the polar zones they exhibit high acid-stable ATPase activity. The SDH activity varies from moderate to high. The chain fibres exhibit high alkali-stable and low acid-stable ATPase and high SDH activity in the extensor digitorum longus muscle, whereas in the soleus muscle the acid-stable ATPase activity varies from a low one to a high one, either among individual chain fibres in one spindle, and/or repeatedly along the fibre length. Since there are regional differences in morphological characteristics and in staining properties of intrafusal fibres, a reliable identification of intrafusal fibre types can only be achieved by an analysis of serial sections.     

GABAergic cell types in the lizard hippocampus.

The neurochemical classification of GABAergic cells in the lizard hippocampus resulted in a further division into four major, non-overlapping subtypes. Each GABAergic cell subtype displays specific targets on the principal hippocampal neurons. The synaptic targets of the GABA/neuropeptide subtype are the distal apical dendrites of principal neurons. Calretinin- and parvalbumin-containing GABAergic cells synapse on the cell body and proximal dendrites of principal cells. Calbindin is expressed in a distinct group of interneurons, the synapses of which are directed to the dendrites of principal neurons. Finally, another subtype displays NADPH-diaphorase activity, but its synaptic target has not been established.     

T cell differentiation antigens on lymphocytes in the human intestinal lamina propria.

Recently, T cell subpopulations presumably representing memory T lymphocytes have been described in vitro. Intestinal lamina propria T cells (LP-T) have characteristics resembling those of memory cells. We therefore investigated the expression of surface Ag associated with memory phenotype in vitro on lamina propria lymphocytes (LPL) and PBL and on the T cell subpopulations defined by the bright expression of CD45R0 by flow cytometric analysis of isolated cell populations. LPL had significantly increased percentages of CD45R0 and CD58 positive cells compared with PBL. Whereas PBL showed bimodal expression profiles of CD45R0, CD58, and CD2, the vast majority of LPL was bright for these Ag. Expression of CD45RA was significantly reduced in both frequency and intensity in LPL, and LPL had significantly reduced percentages of CD11a/CD18 and CD29 positive cells compared with PBL. The CD45R0 bright T cell subpopulations of both PBL and LPL were characterized by a lack of CD45RA. CD45R0 bright T cells from the peripheral blood (PB-T) were predominantly bright for CD2, CD58, CD29, and CD11a/CD18 whereas CD45R0 dim PB-T had bimodal expression profiles and CD45R0 negative PB-T were dim or even negative for these Ag. CD45R0 bright LP-T were also bright for CD2 and CD58 but had significantly reduced surface densities of CD11a/CD18 and CD29 compared with CD45R0 bright PB-T. The surface density of CD29 on CD45R0 bright LP-T corresponded to that of CD45R0 negative PB-T, and a significant proportion of CD45R0 bright LP-T was even negative for CD11a/CD18 and CD29. Additionally, CD45R0 bright LP-T in contrast to PB-T were characterized by a lack of 1-selectin and the expression of CDw49a and the mucosa-specific T cell Ag HML-1 on high percentages of cells. Our results show that the phenotype of CD45R0 bright T cells from the lamina propria clearly deviates from that of memory T cells in vitro and of CD45R0 bright T cells in the peripheral blood. We conclude that memory T cell populations in vivo undergo specific differentiation depending on their tissue localization, leading to unique phenotypic and presumably functional features.     

Plant CSR types in the north: comparing the morphological and morpho-physiological approaches

Grime’s competition–stress–ruderal (CSR) theory is widely used to study plant species’ responses to multiple environmental factors. We compared two models to allocate CSR types the global “StrateFy” model (Pierce et al. Funct Ecol, 31:444–457, 2017) and a locally developed morpho-physiological model (Novakovskiy et al. Int J Ecol, p e1323614, 2016). The “StrateFy” model is based on three morphological leaf traits: leaf area (LA), leaf dry matter content (LDMC) and specific leaf area (SLA). The morpho-physiological model additionally uses plant height (PH), leaf dry weight (LDW), photosynthetic capacity (PN) and respiration rate (RD), leaf nitrogen, and carbon concentration (LNC, LCC). We applied both models to 74 plant species, the traits of which were measured at mountain (Northern Urals) and plane (Komi Republic, Russia) landscapes of European Northeast. The comparison of the calculated C, S, and R scores showed two groups of species with large and unidirectional differences. The first group consists of species with a shift from S (morpho-physiological model) to CR (StrateFy model) strategy. Species of this group are typical for deep shaded habitats and characterized by low LDMC (10–25%) and high SLA (30–60 mm² mg⁻¹). The second group consists of C species (morpho-physiological model) which were classified as S (StrateFy model) strategy. This group includes mainly tall shrubs, graminoids, and forbs with relatively small leaves (300–2000 mm²). In our opinion, the CSR strategies obtained by the morpho-physiological model showed better agreement with the basic principles underlying Grime''s theory. The use of a limited number of morphological traits (LA, LDMC, SLA) in the StrateFy model does not always allow to determine the life strategy correctly. For example, these traits are insufficient for a clear separation of deeply shaded stress-tolerant species and ruderals. On the other hand, the use of the morpho-physiological model requires a large number of field measurements, which makes it difficult to use this model to allocate CSR strategies for a large number of species.Supplementary InformationThe online version contains supplementary material available at 10.1007/s12298-021-00973-9.     

Gastrointestinal hormones in birds: morphological, chemical, and developmental aspects

Historically, the enterochromaffin cell was the first endocrine cell type detected in avian gut; subsequently, a number of types of such cells were distinguished on the basis of the ultrastructural features of the secretory granules. More recently, immunocytochemical procedures have revealed somatostatin-, pancreatic polypeptide (PP)-, polypeptide YY-, glucagon-, secretin-, vasoactive intestinal peptide (VIP)-, gastrin-, cholecystokinin-, neurotensin-, bombesin-, substance P-, enkephalin-, motilin-, and FMRFamide-like immunoreactivity in avian gastrointestinal endocrine cells. Most endocrine cells are located in the antrum; there are a number in the proventriculus and small intestine but few in the gizzard, cecum, and rectum. Several avian gastroenteropancreatic hormones, including glucagon, VIP, secretin, bombesin, neurotensin, and PP, have been isolated and sequenced. They resemble the equivalent mammalian peptides in terms of molecular size but differ in amino acid composition and sequence; some (e.g., VIP) differ only in minor respects, others (e.g., secretin) more radically. Gastrointestinal endocrine cells appear late in development; available data indicate that few types are recognized by either immunocytochemistry or electron microscopy before 16 days of incubation. Experimental evidence has shown that at least the majority of gut endocrine cells are of endodermal origin and are not derived from the neural crest or neuroectoderm as earlier proposed. In early embryos, the progenitors of gastrointestinal endocrine cells are more widespread than are the differentiated cells in chicks at hatching. This, along with other observations, raises the question of factors that might influence the differentiation of gut endocrine cells.     

Neuron-schwann cell interaction in basal lamina formation

The availability of tissue culture systems that allow the growth of nerve cells, Schwann cells, and fibroblasts separately or in various combinations now makes possible investigation of the role of cell interactions in the development of the peripheral nervous system. Using these systems it was earlier found that basal lamina is formed on the Schwann cell surface in cultures of sensory ganglion cells and Schwann cells without fibroblasts. It is here reported that the presence of nerve cells is required for the generation of basal lamina on the Schwann cell plasmalemma. Utilizing nerve cell-Schwann cell preparations devoid of fibroblasts, this was found in the following ways. (1) When nerve cells are removed from 3- to 5-week-old cultures, the basal lamina disappears from Schwann cells. (2) If nerve cells are added back to such Schwann cell populations, Schwann cell basal lamina reappears. (3) Removal of nerve cells from older (3–4 months) cultures does not lead to basal lamina loss; areas presumed not to have been coated with lamina before neurite degeneration remain so, suggesting that the lamina persists but is not reformed. (4) If basal lamina is removed with trypsin, it is reformed in neuron plus Schwann cell cultures but not in Schwann cell populations alone. Thus, the formation but not the persistence of Schwann cell basal lamina requires the presence of nerve cells.     

Relevance of plant lectins in human cell biology and immunology.

Protein-carbohydrate interactions are used for intercellular communication. Mammalian cells are known to bear a variety of glycoconjugates. Lectins, first discovered in plants, are proteins which can specifically bind carbohydrates. Given the high affinity of plant lectins for carbohydrates, they have always been important as molecular tools in the identification, purification and stimulation of specific glycoproteins on human cells. Lectins have provided important clues to the repertoire of carbohydrate structures in animal cells. The discovery of plant lectins gave a great impulse to modern glycobiology. They represent important biochemical reagents for numerous applications in the biomedical field and in research. Sequence determinations and structural characterization helped to understand the mechanism of action in many biologic systems. Plant lectins have been fundamental in human immunological studies because some of them are mitogenic/activating to lymphocytes. Understanding the molecular basis of lectin-carbohydrate interactions and of the intracellular signalling evoked holds promise for the design of novel drugs for the treatment of infectious, inflammatory and malignant diseases. It may also be of help for the structural and functional investigation of glycoconjugates and their changes during physiological and pathological processes.     

Two morphological types of cell appendages on a strongly adhesive bacterium, Acinetobacter sp. strain Tol 5

Two morphological types of appendages, an anchor-like appendage and a peritrichate fibril-type appendage, have been observed on cells of an adhesive bacterium, Acinetobacter sp. strain Tol 5, by use of recently developed electron microscopic techniques. The anchor extends straight to the substratum without branching and tethers the cell body at its end at distances of several hundred nanometers, whereas the peritrichate fibril attaches to the substratum in multiple places, fixing the cell at much shorter distances.     

Heat-induced morphological and biochemical changes in the nuclear lamina from Ehrlich ascites tumor cells in vivo

Membrane-depleted nuclei from Ehrlich ascites tumor (EAT) cells isolated at low ionic strength in the presence of EDTA exhibit highly decondensed chromatin fibers and a loss of morphologically identifiable nucleoli. Treatment of these nuclei with nucleases and 2 M NaCl followed by low-speed centrifugation permitted the facile isolation of the nuclear lamina layer. Under the same conditions, but after heat-shock treatment of the living cells, the chromatin appears in a more condensed state, the nucleoli are well-defined, and the nuclear lamina layer was destabilized in concert with the appearance of an internal nuclear matrix and nucleolar skeleton. Furthermore, we also found both an increase in the protein mass as well as the appearance of a relatively large number of new proteins in this fraction, which are phosphorylated. The major proteins of the nuclear lamina, the lamins, and the residual vimentin remained insoluble. These heat-shock-induced changes were also accompanied by a dephosphorylation of lamins A and C but not of lamin B.