The B-chromosomes of Neopodismopsis abdominalis (Orthoptera,Acrididae)

As an extension of an earlier study, the behaviour of two kinds of supernumerary chromosomes has been re-examined in populations of Neopodismopsis abdominalis (Acrididae) from Ontario. One of these is minute and metacentric (B^S); the other is large and heterochromatic (B^L). The B^S has a 40% probability of undergoing precocious separation when present as a univalent. This separation may lead to restitution and subsequently to macrospermatid formation. The frequency of macrospermatids was a power function of the number of precocious B^S elements per cell and approached 20% in 4B^S-individuals. Individuals with high numbers of B^S occur in slight excess of Poisson expectation possibly reflecting a mechanism which compensates for the detrimental effects of the B^S. The B^L, by contrast, does not undergo precocious division and neither micro- nor macro-spermatids ascribable to the B^L were seen. Non-disjunction of B-chromosomes occurred very rarely and was seen in only three B^S individuals out of 141 examined and in only two B^L individuals out of 33. Moreover it was equally frequent in caeca and gonad and did not result in a net loss or a net gain of B-chromosomes in the germ line.     

A propos de l'article ‘The B-chromosomes of Locusta migratoria I. Detection of negative correlation between mean chiasma frequency and the rate of accumulation of the B's; a reanalysis of the available data about the transmission of these B-chromosomes’, par. J. Cabrero,E. Viseras et J. P. M. Camacho

Comment on the article ‘The B-chromosomes of Locusta migratoria I. Detection of negative correlation between mean chiasma frequency and the rate of accumulation of the B's; a reanalysis of the available data about the transmission of these B-chromosomes’ — Some critical remarks on the said article (published in Genetica 64: 155–164, 1984) are presented.     

Chromosome banding in Amphibia

The mitotic and meiotic chromosomes of the marsupial frog Gastrotheca riobambae were analysed with various banding techniques. The karyotype of this species is distinguished by considerable amounts of constitutive heterochromatin and unusual, heteromorphic XY sex chromosomes. The Y chromosome is considerably larger than the X chromosome and almost completely heterochromatic. The analysis of the banding patterns obtained with GC- and AT-base-pair-specific fluorochromes shows that the constitutive heterochromatin in the Y chromosome consists of at least three different structural categories. The only nucleolus organizer region (NOR) of the karyotype is localized in the short arm of the X chromosome. This causes a sex-specific difference in the number of NOR: female animals have two NORs in diploid cells, male animals one. No cytological indications were found for the inactivation of one of the two X chromosomes in the female cells. In male meiosis, the heteromorphic sex chromosomes form a characteristic sex-bivalent by pairing their telomeres in an end-to-end arrangement. The significance of the XY/XX sex chromosomes of G. riobambae for the study of X-linked genes in Amphibia, the evolution of sex chromosomes and their specific DNA sequences, and the significance of the meiotic process of sex chromosomes are discussed.     

Intranuclear destruction of heterochromatin in two species of armored scale insects

Spermatogenesis is described in two species of armored scale insects,Parlatoria proteus andParlatoria ziziphus. In the males of both species, a haploid set of four chromosomes becomes heterochromatic during early embryogeny. The heterochromatic chromosomes are lost later by two different mechanisms during spermatogenesis. Just before meiosis begins one or more heterochromatic chromosomes disappear from each primary spermatocyte as a consequence of a rapid intranuclear chromosome destruction. Meiosis consists of a single achiasmatic division. At prophase four euchromatic and from one to three heterochromatic chromosomes are present in each cell. Although both the euchromatic and remaining heterochromatic chromosomes divide, the heterochromatic chromosomes are later eliminated by posttelophase ejection; the eliminated chromosomes then disintegrate slowly in the cytoplasm. Each of the two species displays a species specific level of heterochromatin retention and both differ in this regard from the previously describedParlatoria oleae. The evolution of a chromosome system involving intranuclear chromosome destruction is discussed.     

Heterochromatic Regions of Maize A- and B-Chromosomes

A collection of maize forms from the Vavilov All-Russia Institute of Plant Breeding (VIR) was studied. We compared variation in the following traits: the number and size of heterochromatic knob regions (HKs) of chromosomes of mother pollen cells at pachytene depending on the presence (B⁺) or absence (B⁰) of B-chromosomes; size of B-chromosomes (general, of heterochromatic part); and the frequency of B⁺ plants in groups of forms contrasting in the HK number (10–15, 4–10, 2–7, 1–4). It was shown that B chromosomes had statistically significantly different effects on HK polymorphism, relative heterochromatin content in the cell of multiknob and knobless forms, selection of plants for early ear flowering in these forms. The combination of maximum (and minimum) sizes of heterochromatic regions of A- and B-chromosomes was established; the genomic level of control of the trait is suggested. The role of the relationship of polymorphism at heterochromatic regions of A- and B-chromosomes between them and with the systems of maize reproduction is considered as a mechanism of maintenance of optimum plant heterozygosity via adaptive ontogenetic redistribution of heterochromatin among loci, chromosomes, and gametes.     

Cellular promiscuity: explaining cellular fidelity in vivo against unrestrained pluripotency in vitro

The differentiation of pluripotent stem cells into various progeny is perplexing. In vivo, nature imposes strict fate constraints. In vitro, PSCs differentiate into almost any phenotype. Might the concept of ‘cellular promiscuity'' explain these surprising behaviours?John Gurdon''s [1] and Shinya Yamanaka''s [2] Nobel Prize involves discoveries that vex fundamental concepts about the stability of cellular identity [3,4], ageing as a rectified path and the differences between germ cells and somatic cells. The differentiation of pluripotent stem cells (PSCs) into progeny, including spermatids [5] and oocytes [6], is perplexing. In vivo, nature imposes strict fate constraints. Yet in vitro, reprogrammed PSCs liberated from the body government freely differentiate into any phenotype—except placenta—violating even somatic cell against germ cell segregations. Albeit that it is anthropomorphic, might the concept of ‘cellular promiscuity'' explain these surprising behaviours?Fidelity to one''s differentiated state is nearly universal in vivo—even cancers retain some allegiance. Appreciating the mechanisms in vitro that liberate reprogrammed cells from the numerous constraints governing development in vivo might provide new insights. Similarly to highway guiderails, a range of constraints preclude progeny cells within embryos and organisms from travelling too far away from the trajectory set by their ancestors. Restrictions are imposed externally—basement membranes and intercellular adhesions; internally—chromatin, cytoskeleton, endomembranes and mitochondria; and temporally by ageing.‘Cellular promiscuity'' was glimpsed previously during cloning; it was seen when somatic cells successfully ‘fertilized'' enucleated oocytes in amphibians [1] and later with ‘Dolly'' [7]. Embryonic stem cells (ESCs) corroborate this. The inner cell mass of the blastocyst cells develops faithfully, but liberation from the trophoectoderm generates pluripotent ESCs in vitro, which are freed from fate and polarity restrictions. These freedom-seeking ESCs still abide by three-dimensional rules as they conform to chimaera body patterning when injected into blastocysts. Yet if transplanted elsewhere, this results in chaotic teratomas or helter-skelter in vitro differentiation—that is, pluripotency.August Weismann''s germ plasm theory, 130 years ago, recognized that gametes produce somatic cells, never the reverse. Primordial germ cell migrations into fetal gonads, and parent-of-origin imprints, explain how germ cells are sequestered, retaining genomic and epigenomic purity. Left uncontaminated, these future gametes are held in pristine form to parent the next generation. However, the cracks separating germ and somatic lineages in vitro are widening [5,6]. Perhaps, they are restrained within gonads not for their purity but to prevent wild, uncontrolled misbehaviours resulting in germ cell tumours.The ‘cellular promiscuity'' concept regarding PSCs in vitro might explain why cells of nearly any desired lineage can be detected using monospecific markers. Are assays so sensitive that rare cells can be detected in heterogeneous cultures? Certainly population heterogeneity is considered for transplantable cells—dopaminergic neurons and islet cells—compared with applications needing few cells—sperm and oocytes. This dilemma of maintaining cellular identity in vitro after reprogramming is significant. If not addressed, the value of unrestrained induced PSCs (iPSCs) as reliable models for ‘diseases in a dish'', let alone for subsequent therapeutic transplantations, might be diminished. X-chromosome re-inactivation variants in differentiating human PSCs, epigenetic imprint errors and copy number variations are all indicators of in vitro infidelity. PSCs, which are held to be undifferentiated cells, are artefacts after all, as they undergo their programmed development in vivo.If correct, the hypothesis accounts for concerns raised about the inherent genomic and epigenomic unreliability of iPSCs; they are likely to be unfaithful to their in vivo differentiation trajectories due to both the freedom from in vivo developmental programmes, as well as poorly characterized modifications in culture conditions. ‘Memory'' of the PSC''s identity in vivo might need to be improved by using approaches that might not fully erase imprints. Regulatory authorities, including the Food & Drug Administration, require evidence that cultured PSCs do retain their original cellular identity. Notwithstanding fidelity lapses at the organismal level, the recognition that our cells have intrinsic freedom-loving tendencies in vitro might generate better approaches for only partly releasing somatic cells into probation, rather than full emancipation.     

The nucleolus organizer region of maize (Zea mays L.)

Maize plants were produced partially triploid for the heterochromatic segment of the nucleolus organizer region (NOR) or partially triploid or tetraploid for the site giving rise to the secondary constriction of the NOR. These partially hyperploid plants were characterized in terms of chromosome and/or nucleolar constitution by light microscopy at pachytene, diakinesis, and quartet stages of microsporogenesis. DNA's of the various partially hyperploid plants and appropriate controls were extracted and hybridized with ³H-rRNA. The heterochromatic segment of the NOR was found to contain most of the rRNA cistrons, but has little or no interaction with the nucleolus. In contrast with the heterochromatic segment, the site giving rise to the secondary constriction contains few rRNA cistrons but is active in nucleolar formation as viewed at pachytene, diakinesis and quartet stages.     

A description of genealogical rank changes in a troop of Japanese monkeys (Macaca fuscata)

Rank changes among females of a troop of 154 Japanese monkeys (Macaca fuscata) are described. A medium ranking female, with support from the alpha male, successfully challenged the alpha female. Following this dominance shift, almost all members of the two genealogical groups underwent rank changes. The observations provide some evidence that the role of alpha female may be competed for, just as the alpha male position is, in macaque social groups.     

IL17A impairs blood–testis barrier integrity and induces testicular inflammation

Experimental autoimmune orchitis is a useful model for studying testicular inflammation and germ/immune cell interactions. Th17 cells and their hallmark cytokine IL17A were reported to be involved in the development of autoimmune orchitis. The aim of the present work is to investigate the pathogenic role of IL17A in rat testis. In vitro experiments were performed in order to analyze effects of IL17A on Sertoli cell tight junctions. The addition of IL17A to normal rat Sertoli cell cultures induced a significant decline in transepithelial electrical resistance and a reduction of occludin expression and redistribution of occludin and claudin 11, altering the Sertoli cell tight junction barrier. Intratesticular injection of 1 μg of recombinant rat IL17A to Sprague–Dawley rats induced increased blood–testis barrier permeability, as shown by the presence of biotin tracer in the seminiferous tubule adluminal compartment, and delocalization of occludin and claudin 11. Results showed that IL17A induced focal inflammatory cell infiltration in the interstitium and germ cell sloughing in adjacent seminiferous tubules. Moreover, an increase in TUNEL+ apoptotic germ cells was also observed. Inflammatory ED1+ macrophages were the main population infiltrating the interstitium following IL17A injection. This correlated with an increase in mRNA expression of the monocyte chemoattractant protein Ccl2, its receptor Ccr2 and the vascular cell adhesion molecule Vcam1. Overall results suggest a relevant role of IL17A in the development of testicular inflammation, facilitating the recruitment of immune cells to the testicular interstitium and inducing impairment of blood–testis barrier function.     

Gonadal morphology of threadfin breams,Nemipterus bathybius andN. virgatus: Evidence of rudimentary hermaphroditism

Gonads of young and adultNemipterus bathybius andN. virgatus were examined histologically. In youngN. bathybius males, the testis is composed of a dorsal and a ventral zone separated by thin connective tissue. A duct runs through the center of the dorsal zone, and has an opening on the ventromedian surface of the body, separate from the male genital pore. Along with the start of spermatogenesis in the ventral zone, germ cells distributed in the dorsal zone also begin spermatogenesis and eventually develop into spermatozoa. Consequently, in mature testes the sperm sinuses are formed to enclose the dorsal duct, leaving a small number of germ cells, including oviform cells, retained in the lamellar projections of the duct. Testes ofNvirgatus also have essentially the same histological characteristics. No trace of testicular tissue is present in the ovaries, except in four cases of intersexual gonads found in both nemipterid species. It is concluded that the dorsal duct and its lamellar projections are remnants of the ovarian cavityoviduct system and ovigerous lamellae of the ovarian portion of the gonad, and that these two nemipterid species are rudimentary hermaphrodites in which males have bisexual gonads of the delimited type in their juvenile stages.     

Construction and Quantitative Evaluation of a Dual Specific Promoter System for Monitoring the Expression Status of Stra8 and c-kit Genes

Applications of genetic constructs with multiple promoters, which are fused with reporter genes and simultaneous monitoring of various events in cells, have gained special attention in recent years. Lentiviral vectors, with their distinctive characteristics, have been considered to monitor the developmental changes of cells in vitro. In this study, we constructed a novel lentiviral vector (FUM-M), containing two germ cell-specific promoters (Stra8 and c-kit), fused with ZsGreen and DsRed2 reporter genes, and evaluated its efficiency in different cells following treatments with retinoic acid and DMSO. Several cell lines (P19, GC-1 spg and HEK293T) were transduced with this vector, and functional capabilities of the promoters were verified by flow cytometry and quantitative RT-PCR. Our results indicate that FUM-M shows dynamic behavior in the presence and absence of extrinsic factors. A correlation was also observed between the function of promoters, present in the lentiviral construct and the endogenous level of the Stra8 and c-kit mRNAs in the cells. In conclusion, we recommend this strategy, which needs further optimization of the constructs, as a beneficial and practical way to screen chemical inducers involved in cellular differentiation toward germ-like cells.     

Marker features for malignancy in ectocervical cells

Marker features for malignancy have recently been observed in ectocervical cells, even in cells that are visually normal in appearance. This study assessed the statistical significance of these marker features using a mixed-model nested-design analysis of variance (ANOVA). Features in blue intermediate cells from patients with normal cytology, moderate dysplasia, and severe dysplasia/carcinomain situ, nonkeratinizing cells from patients with moderate dysplasia, severe dysplasia/carcinomain situ, and invasive cancer, and dysplastic cells from areas of metaplasia from patients with moderate dysplasia, severe dysplasia/carcinomain situ, and invasive cancer were tested. ANOVA clearly demonstrated that the marker features differentiate between cells of the same cell type originating from patients in different diagnostic categories. In every instance, the differences owing to the diagnostic category were statistically significantly greater than those caused by patient-to-patient variability. Although the discriminating marker features in the intermediate cells were almost exclusively spectral features reflecting staining differences, morphometric features were also marker features in the dysplastic cells.     

The chromosomal localisation of satellite DNA in Ptyas mucosus (Ophidia,Colubridae)

Ptyas mucosus male DNA has a repetitious DNA satellite (p= 1.700 g cm^?3) constituting 5% of the haploid genome. In situ hybridisation of radioactive complementary RNA (cRNA) has revealed that satellite sequences are located in the centromeric region of one pair of macrochromosomes and in the terminal region of 8 pairs of microchromosomes. These regions are constitutively heterochromatic as revealed by C-banding. The possibility of involvement of satellite rich microchromosomes in nucleolus organisation is discussed.     

Probiotic Properties of Lactobacillus crispatus 2,029: Homeostatic Interaction with Cervicovaginal Epithelial Cells and Antagonistic Activity to Genitourinary Pathogens

Lactobacillus crispatus 2029 isolated upon investigation of vaginal lactobacilli of healthy women of reproductive age was selected as a probiotic candidate. The aim of the present study was elucidation of the role of L. crispatus 2029 in resistance of the female reproductive tract to genitourinary pathogens using cervicovaginal epithelial model. Lactobacillus crispatus 2029 has surface layers (S-layers), which completely surround cells as the outermost component of their envelope. S-layers are responsible for the adhesion of lactobacilli on the surface of cervicovaginal epithelial cells. Study of interactions between L. crispatus 2029 and a type IV collagen, a major molecular component of epithelial cell extracellular matrix, showed that 125I-labeled type IV collagen binds to lactobacilli with high affinity (Kd = (8.0 ± 0.7) × 10^?10 M). Lactobacillus crispatus 2029 consistently colonized epithelial cells. There were no toxicity, epithelial damage and apoptosis after 24 h of colonization. Electronic microscope images demonstrated intimate association between L. crispatus 2029 and epithelial cells. Upon binding to epithelial cells, lactobacilli were recognized by toll-like 2/6 receptors. Lactobacillus crispatus induced NF-κB activation in epithelial cells and did not induce expression of innate immunity mediators IL-8, IL-1β, IL-1α and TNF-α. Lactobacillus crispatus 2029 inhibited IL-8 production in epithelial cells induced by MALP-2 and increased production of anti-inflammatory cytokine IL-6, maintaining the homeostasis of female reproductive tract. Lactobacillus crispatus 2029 produced H₂O₂ and provided wide spectrum of antagonistic activity increasing colonization resistance to urinary tract infections by bacterial vaginosis and vulvovaginal candidiasis associated agents.     

The Golgi apparatus mediates the transport of phytohemagglutinin to the protein bodies in bean cotyledons

When developing cotyledons of Phaseolus vulgaris L. were labeled with [³H]fucose, fucose-labeled phytohemagglutinin (PHA) was found in organelles with average densities of 1.13 g cm^-3 and 1.22 g cm^-3. The position of these organelles on isopycnic sucrose gradients was independent of the presence of MgCl₂ and ethylenediaminetetraacetate in the media, indicating that the fucose-labeled PHA was not associated with the rough endoplasmic reticulum (ER). The organelles with a density of 1.13 g cm^-3 were identified as membranes of the Golgi apparatus on the basis of the similarity of their sedimentation properties and those of the Golgi marker enzyme, inosine diphosphatase, in both isopycnic and rate-zonal sucrose gradients. The organelles with a density of 1.22 g cm^-3 were identified as small (0.1–0.4 μm), electron-dense vesicles with a protein content similar to that of the protein bodies. Pulsechase experiments with [³H]fucose indicated that fucose-labeled PHA first appeared in the Golgi-apparatus-derived membranes and later in the dense vesicles. Fucose-labeled PHA chased out of the Golgi apparatus first, then out of the dense vesicles, and accumulated in the soluble portion of the homogenate which contained the contents of the broken protein bodies. Fucose-labeled PHA chased out of the two types of organelles with a t _1/2 of 20–30 min, a rate three to four times faster than newly synthesized PHA chases out of the bulk of the ER (Chrispeels, M.J., Bollini, R., 1982, Plant Physiol. 70, 1425–1428). This result indicates that the Golgi apparatus is a much smaller compartment than the ER in the storage parenchyma cells. The sodium ionophore, monensin, which interferes with the function of the Golgi apparatus of animal cells, blocks the biosynthesis and—or transport of fucose- and galactose-labeled macromolecules to the cotyledon cell walls. Monensin also blocks the transport of labeled PHA out of the Golgi apparatus and into the protein bodies. These results provide the first biochemical evidence that a specific storage protein which accumulates in seeds is modified in, and passes through, the Golgi apparatus on its way to the protein bodies.     

Preparation of protoplast-like structures from conidia ofFusarium culmorum

Protoplast-like structures have been formed by digestion of the cell walls ofFusarium culmorum conidia by lytic enzyme preparations ofMicromonospora AS. Under the test conditions extrusion of the protoplasts was not observed. It seems that digestion of the cell wall occurs in different stages. Digestion of the septa preceded the formation of protoplasts of the individual cells of the multicellularF. culmorum conidia. A few protoplasts survived the lytic enzyme treatment. “Protoplasts” obtained from conidia are much more stable than those obtained from young hyphae and were able to germinate with the formation of normal mycelium. Lysis of some of the protoplast bodies led to the formation of a membranous structure. The protoplasts derived from each of the constituent cells of the conidia could be isolated with the micromanipulator. No differences were found in the ability of the isolated cells to germinate.     

DNA replication,G- and C-bands and meiotic behaviour of supernumerary chromosomes of Rattus rattus (Linn.)

Supernumerary chromosomes have been observed in a few individuals of three subspecies of Rattus rattus from India and Nepal. The supernumerary chromosomes are late replicating and positively heteropycnotic during meiosis which characterize their heterochromatic nature. Their G-banding patterns do not exactly resemble the patterns exhibited by the chromosomes of similar size and morphology of the normal complement. The supernumerary chromosomes become conspicuous for the lack of a centromeric C-band in them as compared to the prominent C-bands in other chromosomes of the complement.