Griffonia simplicifolia lectins bind specifically to endothelial cells and some epithelial cells in mouse tissues

Summary The binding ofGriffonia simplicifolia agglutinin-I (GSA—I) and the isolectins GSA-I-AB₃ and GSA-I-B₄, having affinity for some -d-galactosyl andN-acetyl galactosaminyl residues was studied in different mouse tissues. In brain, cardiac muscle and skeletal muscle, the GSA-I-lectin conjugates showed prominent binding only to blood vessel endothelia. Similarly, in the liver and kidney cortex the GSA-I-conjugates selectively reacted with endothelial cells of the sinusoids and with intertubular and glomerular capillaries, respectively. However, a strong reactivity with the GSA-I-conjugates was additionally seen in the acinar cells of the pancreas, in the stratified squamous epithelia of skin and tongue, and in transitional epithelium. SDS—PAGE electrophoresis combined with the lectin-blotting technique indicated that a similar set of glycoproteins are responsible for the GSA-I binding, even in different tissues. Another lectin with specificity for -d-galactose, theMaclura pomifera agglutinin, displayed a distinctly different distribution of binding sites, mainly in the basement membranes, of all mouse tissues studied. The results suggest that some -d-galactosyl residues, recognized by the binding of GSA-I lectins, are preferentially expressed in endothelial cells of mouse tissues, and also provide further evidence that endothelial cells can present a highly specific surface glycosylation pattern.     

Effect of hydrocortisone on the ultrastructure of the small,intensely fluorescent,granule-containing cells in cultures of sympathetic ganglia of newborn rats

Summary Sympathetic chain ganglia of newborn rats were cultured in Rose chambers with or without hydrocortisone. After one week, the cultures were examined by light microscopy for formaldehyde-induced catecholamine fluorescence and by electron microscopy after fixation in 5% glutaraldehyde solution and thereafter in 1% osmium tetroxide. Hydrocortisone (10 mg/l) caused a great increase in the number of the small, intensely fluorescent (SIF) cells in the ganglion explants, and the fluorescence intensity of these cells was also increased. The SIF cells corresponded to small, granule-containing (SGC) cells in the electronmicros copic preparations, and in addition to an increase in their number there was also an increase in the size and number of granular vesicles in the presence of hydrocortisone. In control cultures the granular vesicles were round (about 100 nm in diameter) or elongated (40–150 nm in cross section and 150–250 nm in length); both types of vesicles contained electron dense cores. In hydrocortisone-containing cultures round granular vesicles up to 200 nm in diameter were also observed; the cores of these vesicles were of variable electron density. It is concluded that in tissue culture, hydrocortisone causes an increased formation of catecholamine-containing granular vesicles in SIF-SGC cells and their precursors and an increase in the number of these cells.This work was supported by grants from the National Heart Foundation, the Australian Research Grants Committee and the Sigrid Juselius Foundation.University of Melbourne Senior Research Fellow, September, 1971 – August, 1972; present address: Department of Anatomy, University of Helsinki, Siltavuorenpenger, Helsinki, Finland, 00170.Holder of a grant from the National Health and Medical Research Council of Australia.Sunshine Foundation and Rowden White Research Fellow in the University of Melbourne, September, 1971 – August, 1972; present address: Department of Anatomy, University of Helsinki, Siltavuorenpenger, Helsinki, Finland, 00170.     

Enzymatic accessibility of xylans in lignocellulosic materials

The hydrolysis of fibre-bound and isolated xylans from both birch and pine wood and kraft pulps was studied using purified xylanolytic enzymes of Trichoderma reesei. Despite high enzyme loading, the degree of hydrolysis of fibre-bound substrates did not exceed 20% of the theoretical value, apparently due to limited accessibility of the substrates. The fibre-bound xylans were as equally accessible in softwood as in hardwood pulps. The isolated xylans of wood and kraft pulps could be solubilized more extensively, with a hydrolysis yield of 50–65%. The substitution degree of the isolated xylan substrates was reflected in the different hydrolysis yields obtained by the two xylanases, with isoelectric point (pI) values of 9.0 and 5.5. On the more substituted substrates, i.e. pine kraft xylan and pine wood xylan, the two enzymes acted almost similarly, whereas on the less substituted xylan substrates, such as isolated birch kraft xylan, the pI-9.0 enzyme was more efficient. The side-group-cleaving enzymes increased only moderately the solubilization of the substrates.Correspondence to: L. Viikari     

Enzymatic deacetylation of galactoglucomannans

Several hemicellulolytic microorganisms were screened for their capability of liberating acetyl side groups from native softwood galactoglucomannan. All the microorganisms tested were found to produce an extracellular acetyl glucomannan esterase(s). The highest activity was detected in Schizophyllum commune culture filtrate. However, the enzyme produced by Aspergillus oryzae was most efficient in long-term hydrolysis. Acting alone, the purified esterase of A. oryzae was able to liberate most of the acetic acid from galactoglucomannan. The addition of other galactoglucomannan-degrading enzymes did not affect the action of esterase. On the other hand, the addition of esterase clearly enhanced the action of mannanase and -galactosidase. The purified acetyl esterase of Trichoderma reesei was able to liberate acetic acid from short oligomers of glucomannan, whereas the acetyl xylan esterase of T. reesei was unable to act on glucomannan oligomers of any size. Correspondence to: M. Tenkanen     

Lignin release and photomixotrophism in suspension cultures of Picea abies

The effect of different concentrations of sucrose (0-4%) and of two growth regulators (0–50 μ M 2,4-D and 0–25 μ M kinetin) was tested on growth and chlorophyll content of suspension cultures of Picea abies (L.) Karst. originating from chlorophyllous embryo callus in an elevated CO₂ (2%) atmosphere. A continuous chlorophyllous suspension culture was achieved on a medium containing 2% sucrose and a low level of organic nitrogen (0.25 m M arginine and 0.5 m M glutamine) supplemented with 2,4-D (0.5 μ M ) and kinetin (2.5 μ M ). The same medium with 4% sucrose gave the best growth response, but a negative correlation between chlorophyll level and growth was observed. The chlorophyllous cultures grew slowly in a medium with low (0.5%) sucrose or without any carbohydrate source, suggesting photomixotrophism. A high concentration of kinetin inhibited both growth and chlorophyll synthesis. Release of lignin into the nutrient medium was observed in several experiments, especially in slow-growing cultures supplemented with sucrose. Only a few successive passages of suspensions that produced lignin could be cultured before cell death. The cultures releasing lignin may be unique for studies on synthesis and biodegradation of this very complex compound.     

USP26: a genetic risk factor for sperm X‐Y aneuploidy

Segregation of the largely non‐homologous X and Y sex chromosomes during male meiosis is not a trivial task, because their pairing, synapsis, and crossover formation are restricted to a tiny region of homology, the pseudoautosomal region. In humans, meiotic X‐Y missegregation can lead to 47, XXY offspring, also known as Klinefelter syndrome, but to what extent genetic factors predispose to paternal sex chromosome aneuploidy has remained elusive. In this issue, Liu et al (2021) provide evidence that deleterious mutations in the USP26 gene constitute one such factor.Subject Categories: Cell Cycle, Development & Differentiation, Molecular Biology of Disease

Analyses of Klinefelter syndrome patients and Usp26‐deficient mice have revealed a genetic influence on age‐dependent sex chromosome missegregation during male meiosis.

Multilayered mechanisms have evolved to ensure successful X‐Y recombination, as a prerequisite for subsequent normal chromosome segregation. These include a distinct chromatin structure as well as specialized proteins on the pseudoautosomal region (Kauppi et al, 2011; Acquaviva et al, 2020). Even so, X‐Y recombination fails fairly often, especially in the face of even modest meiotic perturbations. It is perhaps not surprising then that X‐Y aneuploidy—but not autosomal aneuploidy—in sperm increases with age (Lowe et al, 2001; Arnedo et al, 2006), as does the risk of fathering sons with Klinefelter syndrome (De Souza & Morris, 2010).Klinefelter syndrome is one of the most common aneuploidies in liveborn individuals (Thomas & Hassold, 2003). While most human trisomies result from errors in maternal chromosome segregation, this is not the case for Klinefelter syndrome, where the extra X chromosome is equally likely to be of maternal or paternal origin (Thomas & Hassold, 2003; Arnedo et al, 2006). Little is known about genetic factors in humans that predispose to paternal XY aneuploidy, i.e., that increase the risk of fathering Klinefelter syndrome offspring. The general notion has been that paternally derived Klinefelter syndrome arises stochastically. However, fathers of Klinefelter syndrome patients have elevated rates of XY aneuploid sperm (Lowe et al, 2001; Arnedo et al, 2006), implying a persistent defect in spermatogenesis in these individuals rather than a one‐off meiotic error.To identify possible genetic factors contributing to Klinefelter syndrome risk, Liu et al (2021) performed whole‐exome sequencing in a discovery cohort of > 100 Klinefelter syndrome patients, followed by targeted sequencing in a much larger cohort of patients and controls, as well as Klinefelter syndrome family trios. The authors homed in on a mutational cluster (“mutated haplotype”) in ubiquitin‐specific protease 26 (USP26), a testis‐expressed gene located on the X chromosome. Effects of this gene’s loss of function (Usp26‐deficient mice) on spermatogenesis have recently been independently reported by several laboratories and ranged from no detectable fertility phenotype (Felipe‐Medina et al, 2019) to subfertility/sterility associated with both meiotic and spermiogenic defects (Sakai et al, 2019; Tian et al, 2019). With their Klinefelter syndrome cohort findings, Liu et al (2021) also turned to Usp26 null mice, paying particular attention to X‐Y chromosome behavior and—unlike earlier mouse studies—including older mice in their analyses. They found that Usp26‐deficient animals often failed to achieve stable pairing and synapsis of X‐Y chromosomes in spermatocytes, produced XY aneuploid sperm at an abnormally high frequency, and sometimes also sired XXY offspring. Importantly, these phenotypes only occurred at an advanced age: XY aneuploidy was seen in six‐month‐old, but not two‐month‐old Usp26‐deficient males. Moreover, levels of spindle assembly checkpoint (SAC) proteins also reduced in six‐month‐old males. Thus, in older Usp26 null mice, the combination of less efficient X‐Y pairing and less stringent SAC‐mediated surveillance of faithful chromosome segregation allows for sperm aneuploidy, providing another example of SAC leakiness in males (see Lane & Kauppi, 2019 for discussion).Liu et al’s analyses shed some light on what molecular mechanisms may be responsible for the reduced efficiency of X‐Y pairing and synapsis in Usp26‐deficient spermatocytes. USP26 codes for a deubiquitinating enzyme that has several substrates in the testis. Because USP26 prevents degradation of these substrates, their levels should be downregulated in Usp26 null testes. Liu et al (2021) show that USP26 interacts with TEX11, a protein required for stable pairing and normal segregation of the X and Y chromosomes in mouse meiosis (Adelman & Petrini, 2008). USP26 can de‐ubiquitinate TEX11 in vitro, and in Usp26 null testes, TEX11 was almost undetectable. It is worth noting that USP26 has several other known substrates, including the androgen receptor (AR), and therefore, USP26 disruption likely contributes to compromised spermatogenesis via multiple mechanisms. For example, AR signaling‐dependent hormone levels are misregulated in Usp26 null mice (Tian et al, 2019).The sex chromosome phenotypes observed in Usp26 null mice predict that men with USP26 mutations may be fertile, but producing XY aneuploid sperm at an abnormally high frequency, and that spermatogenic defects should increase with age (Fig 1). These predictions were testable, because the mutated USP26 haplotype, present in 13% of Klinefelter syndrome patients, was reasonably common also in fertile men (7–10%). Indeed, sperm XY aneuploidy was substantially higher in fertile men with the mutated USP26 haplotype than in those without USP26 mutations. Some mutation carriers produced > 4% aneuploid sperm. Moreover, age‐dependent oligospermia was also found associated with the mutated USP26 haplotype.Open in a separate windowFigure 1Mutated USP26 as genetic risk factor for age‐dependent X‐Y defects in spermatogenesisMouse genetics demonstrate that deleterious USP26 mutations lead to less‐efficient X‐Y pairing and recombination with advancing age. Concomitant decrease of spindle assembly checkpoint (SAC) protein levels leads to less‐efficient elimination of metaphase I spermatocytes that contain misaligned X and Y chromosomes. This allows for the formation of XY aneuploid sperm in older individuals and subsequently increased age‐dependent risk for fathering Klinefelter syndrome (KS) offspring, two correlates also observed in human USP26 mutation carriers. At the same time, oligospermia/subfertility also increases with advanced age in both Usp26‐deficient mice and USP26 mutation‐carrying men, tempering Klinefelter syndrome offspring risk but also decreasing fecundity.As indicated by its prevalence in the normal control population, the USP26 mutated haplotype is not selected against in the human population. With > 95% of sperm in USP26 mutation carriers having normal haploid chromosomal composition, the risk of producing (infertile) Klinefelter syndrome offspring remains modest, likely explaining why USP26 mutant alleles are not eliminated. Given that full Usp26 disruption barely affects fertility of male mice during their prime reproductive age (Felipe‐Medina et al, 2019; Tian et al, 2019; Liu et al, 2021), there is little reason to assume strong negative selection against USP26 variants in humans. USP26 as the first‐ever genetic risk factor predisposing to sperm X‐Y aneuploidy and paternal origin Klinefelter syndrome offspring in humans, as uncovered by Liu et al, may be just one of many. 90% of Liu et al’s Klinefelter syndrome cases were not associated with USP26 mutations. But even in the age of genomics, discovery of Klinefelter syndrome risk factors is not straightforward, since most sperm of risk mutation carriers will not be XY aneuploid and thus not give rise to Klinefelter syndrome offspring. In addition, as Usp26 null mice demonstrate, both genetic and non‐genetic modifiers impact on penetrance of the XY aneuploidy phenotype: Spermatogenesis in the absence of Usp26 was impaired in the DBA/2 but not the C57BL/6 mouse strain background (Sakai et al, 2019), and in older mice, there was substantial inter‐individual variation in the severity of the X‐Y defect (Liu et al, 2021). In human cohorts, genetic and non‐genetic modifiers are expected to blur the picture even more.Future identification of sex chromosome aneuploidy risk factors has human health implications beyond Klinefelter syndrome. Firstly, XXY incidence is not only relevant for Klinefelter syndrome livebirths—it also contributes to stillbirths and spontaneous abortions, at a 4‐fold higher rate than to livebirths (Thomas & Hassold, 2003). Secondly, persistent meiotic X‐Y defects can, over time, result in oligospermia and even infertility. Since the mean age of first‐time fathers is steadily rising and currently well over 30 years in many Western countries, age‐dependent spermatogenic defects will be of ever‐increasing clinical relevance.     

Documenting Freedom From Disease and Re-Establishing a Free Status After a Breakdown Rabies

Rabies reappeared in Finland in the spring of 1988 after a 29-year absence. This time rabies occurred in sylvatic form and the major species involved was the raccoon dog. During the outbreak 1988–89 66 animals were diagnosed rabid. Vaccination of cats, cattle and horses was strongly recommended and vaccination of dogs was compulsory in the outbreak area. A field trial was started on oral immunisation of raccoon dogs and foxes against rabies using baits containing rabies vaccine strain. The outbreak area and a wide buffer zone were baited three times. Finland was declared free of rabies again in 1991. Oral vaccination campaign with vaccine baits has been organised along the southeastern border once a year since the beginning of 90s. Continuous surveillance and epidemiological screening is necessary to detect any new outbreaks of rabies at an early stage.     

Chronic nicotine modifies the effects of morphine on extracellular striatal dopamine and ventral tegmental GABA

Previously, we have shown that 7-week oral nicotine treatment enhances morphine-induced behaviors and dopaminergic activity in the mouse brain. In this study, we further characterized the nicotine-morphine interaction in the mesolimbic and nigrostriatal dopaminergic systems, as well as in the GABAergic control of these systems. In nicotine-pretreated mice, morphine-induced dopamine release in the caudate putamen and nucleus accumbens was significantly augmented, as measured by microdialysis. Chronic nicotine treatment did not change basal extracellular concentrations of dopamine and its metabolites in the caudate putamen and nucleus accumbens, nor did it affect the rate of dopamine synthesis, as assessed by 3-hydroxybenzylhydrazine dihydrochloride-induced DOPA accumulation. GABAergic control of dopaminergic activity was studied by measuring extracellular GABA in the presence of nipecotic acid, an inhibitor of GABA uptake. Acute (0.3 mg/kg or 0.5 mg/kg i.p.) and chronic nicotine, as well as morphine (15 mg/kg s.c.) in control mice decreased nipecotic acid-induced increase in extracellular GABA in the ventral tegmental area/substantia nigra (VTA/SN). In contrast, in nicotine-treated mice, morphine increased GABA levels in the presence of nipecotic acid. We did not find any alterations in GABA(B)-receptor function after chronic nicotine treatment. Thus, our data show that chronic nicotine treatment sensitizes dopaminergic systems to morphine and affects GABAergic systems in the VTA/SN.     

A complete Neandertal mitochondrial genome sequence determined by high-throughput sequencing

A complete mitochondrial (mt) genome sequence was reconstructed from a 38,000 year-old Neandertal individual with 8341 mtDNA sequences identified among 4.8 Gb of DNA generated from approximately 0.3 g of bone. Analysis of the assembled sequence unequivocally establishes that the Neandertal mtDNA falls outside the variation of extant human mtDNAs, and allows an estimate of the divergence date between the two mtDNA lineages of 660,000 +/- 140,000 years. Of the 13 proteins encoded in the mtDNA, subunit 2 of cytochrome c oxidase of the mitochondrial electron transport chain has experienced the largest number of amino acid substitutions in human ancestors since the separation from Neandertals. There is evidence that purifying selection in the Neandertal mtDNA was reduced compared with other primate lineages, suggesting that the effective population size of Neandertals was small.