Basement membrane and epithelial features of fetal-type Leydig cells in rat and human testis

The basement membranes of developing Leydig cells in fetal and newborn testis of rat were studied by ultrastructural and immunocytochemical methods. Fetal-type Leydig cells in prenatal rats were organized in irregularly outlined groups in the interstitium and were extensively surrounded by ultrastructurally identifiable basement membranes and immunocytochemically localized laminin and collagen type IV. Prenatal Leydig cell precursors had small patches of laminin and collagen type IV on their surfaces, which indicated that changes in extracellular matrix took place during their differentiation to mature fetal-type Leydig cells. Additionally, ultrastructural evidence was obtained for a basement membrane surrounding the fetal human Leydig cells similar to that in fetal rats. Soon after birth the rat fetal-type cells gathered into distinct clusters surrounded by delicate envelope cells and a discontinuous basement membrane. Basement-membrane structures, laminin, and collagen type IV were observed between the clustered cells as well. The basement membranes covering large cell surface areas of the fetal-type Leydig cells in fetal and newborn rats differed from those of the adult-type cells, which, according to our earlier study, are covered only by small patches of basement membrane. The difference between the basement membranes of the fetal- and adult-type rat Leydig cells further supports the concept of two different Leydig cell populations. The earlier findings of the epithelial nature of the Leydig cells agree with the observation of basement membranes in the Leydig cells.     

Differentiation of smooth muscle cells in the fetal rat testis and ovary: localization of alkaline phosphatase,smooth muscle myosin,F-actin,and desmin

Summary The histochemical demonstration of alkaline phosphatase (AP) activity and localization of smooth muscle myosin (SMM), F-actin, and desmin were carried out on frozen sections of testes and ovaries from 15-day-old fetal to newborn rats. The presence of immunocytochemically localized SMM and desmin was confirmed by Western blot analysis of proteins from isolated gonads. The development of smooth muscle cells was predominant in the testis. The first SMM-positive cells with an increasing intensity for F-actin and desmin appeared in the testicular tunica albuginea and around the testicular cords by the age of 16 days. A continuous layer of SMM- and F-actin-positive (but not uniformly desmin-positive) myoid cells was detected in the newborn testis. In the early gonads and in the newborn ovary, a majority of the interstitial cells expressed desmin, indicating that, in undifferentiated tissues, non-myogenic cells may also express desmin. During fetal development, male and female gonocytes showed a decrease in F-actin content but retained their high AP activity. In the cortex of the newborn rat ovary, the observed high AP activity and the presence of desmin may be associated with the postnatal histogenesis of the follicles. The presence of SMM-containing cells in the hilus of the ovary may be required for the demarcation of the ovary from the mesonephros by the constriction of the mesovarium. The occurrence of SMM-positive cells predominantly in male fetuses suggests that the development of the contractile cells in the fetal testis may be induced by testicular androgens.     

Light and electron microscopy of the ducts and their subepithelial tissue in the rat ventral prostate

Summary The ducts of the rat ventral prostate have been studied by light and electron microscopy for elucidation of their role in prostatic function. The epithelium of the main duct consists of simple columnar cells and polymorphic basal cells. The columnar cells show no indication of secretory activity. The basal cells contain bundles of filaments of 5–6 nm thickness and numerous pinocytotic vesicles. The ducts are surrounded by layers of circular smooth muscle cells interspersed with nerve axons. On ultrastructural grounds the ducts do not appear to secrete material into the seminal fluid, but apparently the muscular coat actively helps drain the gland during ejaculation.     

Transfer RNA methylase activity in normal and dystrophic chicken muscle

Adult-dystrophic chicken muscle had 30% higher tRNA methylase activity and 42% higher tRNA methylating capacity than normal-adult chicken muscle. Eighty percent of the tRNA methylase activity of the dystrophic muscle resulted in the synthesis of N²-methylguanine, and 9% in the formation of N²,N²-dimethylguanine. From adult-normal muscle extracts, 33% of the tRNA methylase activity was due to the synthesis of N²-methylguanine, and 45% to the formation of N²,N²-dimethylguanine. Eight other methylated bases accounted for 5–15% of the enzyme activity in both tissues. Dialyzed and nondialyzed adult-normal muscle extracts had equivalent tRNA methylase activity. However, the dialyzed extracts synthesized 22% more N²-methylguanine and 18% less N²,N²-dimethylguanine than the nondialyzed extracts. Dialysis had no effect on the tRNA methylase activity or tRNA methylation pattern produced by adult-dystrophic muscle.     

Functional redundancy between flavodiiron proteins and NDH‐1 in Synechocystis sp. PCC 6803

In oxygenic photosynthetic organisms, excluding angiosperms, flavodiiron proteins (FDPs) catalyze light‐dependent reduction of O₂ to H₂O. This alleviates electron pressure on the photosynthetic apparatus and protects it from photodamage. In Synechocystis sp. PCC 6803, four FDP isoforms function as hetero‐oligomers of Flv1 and Flv3 and/or Flv2 and Flv4. An alternative electron transport pathway mediated by the NAD(P)H dehydrogenase‐like complex (NDH‐1) also contributes to redox hemostasis and the photoprotection of photosynthesis. Four NDH‐1 types have been characterized in cyanobacteria: NDH‐1₁ and NDH‐1₂, which function in respiration; and NDH‐1₃ and NDH‐1₄, which function in CO₂ uptake. All four types are involved in cyclic electron transport. Along with single FDP mutants (?flv1 and Δflv3) and the double NDH‐1 mutants (?d1d2, which is deficient in NDH‐1_1,2 and ?d3d4, which is deficient in NDH‐1_3,4), we studied triple mutants lacking one of Flv1 or Flv3, and NDH‐1_1,2 or NDH‐1_3,4. We show that the presence of either Flv1/3 or NDH‐1_1,2, but not NDH‐1_3,4, is indispensable for survival during changes in growth conditions from high CO₂/moderate light to low CO₂/high light. Our results show functional redundancy between FDPs and NDH‐1_1,2 under the studied conditions. We suggest that ferredoxin probably functions as a primary electron donor to both Flv1/3 and NDH‐1_1,2, allowing their functions to be dynamically coordinated for efficient oxidation of photosystem I and for photoprotection under variable CO₂ and light availability.     

An Abscisic Acid-Independent Oxylipin Pathway Controls Stomatal Closure and Immune Defense in Arabidopsis

Plant stomata function in innate immunity against bacterial invasion and abscisic acid (ABA) has been suggested to regulate this process. Using genetic, biochemical, and pharmacological approaches, we demonstrate that (i) the Arabidopsis thaliana nine-specific-lipoxygenase encoding gene, LOX1, which is expressed in guard cells, is required to trigger stomatal closure in response to both bacteria and the pathogen-associated molecular pattern flagellin peptide flg22; (ii) LOX1 participates in stomatal defense; (iii) polyunsaturated fatty acids, the LOX substrates, trigger stomatal closure; (iv) the LOX products, fatty acid hydroperoxides, or reactive electrophile oxylipins induce stomatal closure; and (v) the flg22-mediated stomatal closure is conveyed by both LOX1 and the mitogen-activated protein kinases MPK3 and MPK6 and involves salicylic acid whereas the ABA-induced process depends on the protein kinases OST1, MPK9, or MPK12. Finally, we show that the oxylipin and the ABA pathways converge at the level of the anion channel SLAC1 to regulate stomatal closure. Collectively, our results demonstrate that early biotic signaling in guard cells is an ABA-independent process revealing a novel function of LOX1-dependent stomatal pathway in plant immunity.     

Visual Interactions Conform to Pattern Decorrelation in Multiple Cortical Areas

Neural responses to visual stimuli are strongest in the classical receptive field, but they are also modulated by stimuli in a much wider region. In the primary visual cortex, physiological data and models suggest that such contextual modulation is mediated by recurrent interactions between cortical areas. Outside the primary visual cortex, imaging data has shown qualitatively similar interactions. However, whether the mechanisms underlying these effects are similar in different areas has remained unclear. Here, we found that the blood oxygenation level dependent (BOLD) signal spreads over considerable cortical distances in the primary visual cortex, further than the classical receptive field. This indicates that the synaptic activity induced by a given stimulus occurs in a surprisingly extensive network. Correspondingly, we found suppressive and facilitative interactions far from the maximum retinotopic response. Next, we characterized the relationship between contextual modulation and correlation between two spatial activation patterns. Regardless of the functional area or retinotopic eccentricity, higher correlation between the center and surround response patterns was associated with stronger suppressive interaction. In individual voxels, suppressive interaction was predominant when the center and surround stimuli produced BOLD signals with the same sign. Facilitative interaction dominated in the voxels with opposite BOLD signal signs. Our data was in unison with recently published cortical decorrelation model, and was validated against alternative models, separately in different eccentricities and functional areas. Our study provides evidence that spatial interactions among neural populations involve decorrelation of macroscopic neural activation patterns, and suggests that the basic design of the cerebral cortex houses a robust decorrelation mechanism for afferent synaptic input.     

Vegetation structure and photosynthesis respond rapidly to restoration in young coastal fens

Young coastal fens are rare ecosystems in the first stages of peatland succession. Their drainage compromises their successional development toward future carbon (C) reservoirs. We present the first study on the success of hydrological restoration of young fens. We carried out vegetation surveys at six young fens that represent undrained, drained, and restored management categories in the Finnish land uplift coast before and after restoration. We measured plant level carbon dioxide (CO₂) assimilation and chlorophyll fluorescence (Fv/Fm) from 17 most common plant species present at the sites. Within 5 years of restoration, the vegetation composition of restored sites had started to move toward the undrained baseline. The cover of sedges increased the most in response to restoration, while the cover of deciduous shrubs decreased the most. The rapid response indicates high resilience and low resistance of young fen ecosystems toward changes in hydrology. Forbs had higher photosynthetic and respiration rates than sedges, deciduous shrubs, and grasses, whereas rates were lowest for evergreen shrubs and mosses. The impact of management category on CO₂ assimilation was an indirect consequence that occurred through changes in plant species composition: Increase in sedge cover following restoration also increased the potential photosynthetic capacity of the ecosystem. Synthesis and applications. Restoration of forestry drained young fens is a promising method for safeguarding them and bringing back their function as C reservoirs. However, their low resistance to water table draw down introduces a risk that regeneration may be partially hindered by the heavy drainage in the surrounding landscape. Therefore, restoration success is best safeguarded by managing the whole catchments instead of carrying out small‐scale projects.     

Study of involvement of ImuB and DnaE2 in stationary-phase mutagenesis in Pseudomonas putida

Several bacterial species carry in their genomes a so-called "mutagenesis" gene cluster encoding ImuB which is similar to Y-family DNA polymerases, and DnaE2 related to the catalytic subunit DnaE of Pol III. Y-family DNA polymerases are known to be involved in stationary-phase mutagenesis and DnaE2 homologues characterized so far have expressed a mutator phenotype. In this study, we raised a question about the involvement of ImuB and DnaE2 in stationary-phase mutagenesis. Here, we show that Pseudomonas putida ImuB and DnaE2 have antagonistic effects on stationary-phase mutagenesis. ImuB facilitated accumulation of stationary-phase mutants up to two-fold. In contrast to that, DnaE2 had no significant effect on emergence of 1-bp deletion mutants and moreover, it acted as an anti-mutator in accumulation of base substitution mutants in starving bacteria. Similar antagonistic effects of DnaE2 and ImuB on mutagenesis appeared also in UV-mutagenesis study. This data distinguishes the DnaE2 of P. putida from its homologues studied in other organisms.     

Different protein kinase families are activated by osmotic stresses in Arabidopsis thaliana cell suspensions. Involvement of the MAP kinases AtMPK3 and AtMPK6

Five Ca(2+)-independent protein kinases were rapidly activated by hypoosmotic stress, moderate or high hyperosmolarity induced by several osmolytes, sucrose, mannitol or NaCl. Three of these kinases, transiently activated by hypoosmolarity, recognised by anti-phosphorylated mitogen-activated protein (MAP) kinase antibodies, sensitive to a MAP kinase inhibitor and inactivated by the action of a tyrosine phosphatase, corresponded to MAP kinases. Using specific antibodies, two of the MAP kinases were identified as AtMPK6 and AtMPK3. The two other protein kinases, durably activated by high hyperosmolarity, did not belong to the MAP kinase family. Activation of AtMPK6 and AtMPK3 by hypoosmolarity depended on upstream protein kinases sensitive to staurosporine and on calcium influx. In contrast, these two transduction steps were not involved in the activation of the two protein kinases activated by high hyperosmolarity.