H3K79 methylation directly precedes the histone-to-protamine transition in mammalian spermatids and is sensitive to bacterial infections

In both mammalian and Drosophila spermatids, the completely histone-based chromatin structure is reorganized to a largely protamine-based structure. During this histone-to-protamine switch, transition proteins are expressed, for example TNP1 and TNP2 in mammals and Tpl94D in Drosophila. Recently, we demonstrated that in Drosophila spermatids, H3K79 methylation accompanies histone H4 hyperacetylation during chromatin reorganization. Preceding the histone-to-protamine transition, the H3K79 methyltransferase Grappa is expressed, and the predominant isoform bears a C-terminal extension. Here, we show that isoforms of the Grappa-equivalent protein in humans, rats and mice, that is DOT1L, have a C-terminal extension. In mice, the transcript of this isoform was enriched in the post-meiotic stages of spermatogenesis. In human and mice spermatids, di- and tri-methylated H3K79 temporally overlapped with hyperacetylated H4 and thus accompanied chromatin reorganization. In rat spermatids, trimethylated H3K79 directly preceded transition protein loading on chromatin. We analysed the impact of bacterial infections on spermatid chromatin using a uropathogenic Escherichia coli-elicited epididymo-orchitis rat model and showed that these infections caused aberrant spermatid chromatin. Bacterial infections led to premature emergence of trimethylated H3K79 and hyperacetylated H4. Trimethylated H3K79 and hyperacetylated H4 simultaneously occurred with transition protein TNP1, which was never observed in spermatids of mock-infected rats. Upon bacterial infection, only histone-based spermatid chromatin showed abnormalities, whereas protamine-compacted chromatin seemed to be unaffected. Our results indicated that H3K79 methylation is a histone modification conserved in Drosophila, mouse, rat and human spermatids and may be a prerequisite for proper chromatin reorganization.

Marine litter distribution and density in European seas, from the shelves to deep basins

Anthropogenic litter is present in all marine habitats, from beaches to the most remote points in the oceans. On the seafloor, marine litter, particularly plastic, can accumulate in high densities with deleterious consequences for its inhabitants. Yet, because of the high cost involved with sampling the seafloor, no large-scale assessment of distribution patterns was available to date. Here, we present data on litter distribution and density collected during 588 video and trawl surveys across 32 sites in European waters. We found litter to be present in the deepest areas and at locations as remote from land as the Charlie-Gibbs Fracture Zone across the Mid-Atlantic Ridge. The highest litter density occurs in submarine canyons, whilst the lowest density can be found on continental shelves and on ocean ridges. Plastic was the most prevalent litter item found on the seafloor. Litter from fishing activities (derelict fishing lines and nets) was particularly common on seamounts, banks, mounds and ocean ridges. Our results highlight the extent of the problem and the need for action to prevent increasing accumulation of litter in marine environments.

Experimental Escherichia coli epididymitis in rats: assessment of testicular involvement in a long-term follow-up

The objective of this study was to investigate spermatogenesis and testicular inflammation in a rat model of unilateral Escherichia coli epididymitis in a long-term follow-up. Unilateral epididymitis was induced in 30 Sprague-Dawley rats by injecting E. coli into the right ductus deferens. Oral antimicrobial treatment with sparfloxacin (50 mg kg(-1) body weight/7 days) was administered in half of the animals 24 h after infection. Five treated and five untreated rats were killed at 2 weeks, 3 months and 6 months after infection. Spermatogenesis was investigated using a histological semi-quantitative score. The presence of inflammatory cells (B- and T lymphocytes, macrophages and granulocytes) in the testicular tissues was evaluated by immunohistochemistry. The testes were sterile at all times. Over the course of 6 months, spermatogenesis underwent significant incremental impairment on the inoculated side as compared to the contralateral side (P < 0.001). However, overall spermatogenesis scores were not significantly different between treated and untreated animals (P > 0.3 at each time point). Finally, loss of testicular architecture on the inoculated side was not associated with any cellular inflammatory response. Thus, adjuvant therapies need to be studied, and research is necessary on how to prevent deterioration of testicular function in bacterial epididymitis.

Immune activation in amyloid-β-related angiitis correlates with decreased parenchymal amyloid-β plaque load

BACKGROUND

Primary angiitis of the central nervous system (PACNS) is a rare but serious condition. A fraction of patients suffering from PACNS concurrently exhibit pronounced cerebral amyloid angiopathy (CAA) which is characterized by deposits of amyloid-β (Aβ) in and around the walls of small and medium-sized arteries of the brain. PACNS with CAA has been identified as a distinct disease entity, termed Aβ-related angiitis (ABRA). Evidence points to an immune reaction to vessel wall Aβ as the trigger of vasculitis.

OBJECTIVE

To investigate whether the inflammatory response to Aβ has (1) any effect on the status of immune activation in the brain parenchyma and (2) leads to clearance of Aβ from brain parenchyma.

METHODS

We studied immune activation and Aβ load by quantitative immunohistochemical analysis in brain parenchyma adjacent to affected vessels in 11 ABRA patients and 10 matched CAA controls.

RESULTS

ABRA patients showed significantly increased immune activation and decreased Aβ loads in the brain parenchyma adjacent to affected vessels.

CONCLUSION

Our results are in line with the hypothesis of ABRA being the result of an excessive immune response to Aβ and show that this can lead to enhanced clearance of Aβ from the brain parenchyma by immune-mediated mechanisms.

Abatacept (CTLA-4IG) treatment reduces the migratory capacity of monocytes in patients with rheumatoid arthritis

OBJECTIVE

The binding of abatacept (CTLA-4Ig) to the B7 ligands CD80 and CD86 prevents the engagement of CD28 on T cells and thereby prevents effector T cell activation. In addition, a direct effect of CTLA-4Ig on antigen-presenting cells (APCs) could contribute to the therapeutic effect. To further elucidate the mechanism of CTLA-4Ig, we performed phenotype and functional analyses of APCs in patients with rheumatoid arthritis (RA) before and after the initiation of CTLA-4Ig therapy.

METHODS

Peripheral blood mononuclear cells were analyzed before and at 2 and 4 weeks after the initiation of CTLA-4Ig therapy. Proportions of APCs were determined by flow cytometry. CD14+ monocytes were further analyzed for the expression of costimulatory and adhesion molecules and for their transendothelial migratory capacity in vitro. In addition, CD14+ monocytes from healthy controls were analyzed for their migratory and spreading capacity.

RESULTS

Proportions and absolute numbers of monocytes were significantly increased in RA patients treated with CTLA-4Ig. The expression of several adhesion molecules was significantly diminished. In addition, monocytes displayed a significant reduction in their endothelial adhesion and transendothelial migratory capacity upon treatment with CTLA-4Ig. Likewise, isolated monocytes from healthy controls revealed a significant reduction in their migratory and spreading activity after preincubation with CTLA-4Ig or anti-CD80 and anti-CD86 antibodies.

CONCLUSION

We describe direct effects of CTLA-4Ig therapy on phenotype and functional characteristics of monocytes in RA patients that might interfere with the migration of monocytes to the synovial tissue. This additional mechanism of CTLA-4Ig might contribute to the beneficial effects of CTLA-4Ig treatment in RA patients.

Increase of litter at the Arctic deep-sea observatory HAUSGARTEN

Although recent research has shown that marine litter has made it even to the remotest parts of our planet, little information is available about temporal trends on the deep ocean floor. To quantify litter on the deep seafloor over time, we analysed images from the HAUSGARTEN observatory (79°N) taken in 2002, 2004, 2007, 2008 and 2011 (2500 m depth). Our results indicate that litter increased from 3635 to 7710 items km⁻² between 2002 and 2011 and reached densities similar to those reported from a canyon near the Portuguese capital Lisboa. Plastic constituted the majority of litter (59%) followed by a black fabric (11%) and cardboard/paper (7%). Sixty-seven percent of the litter was entangled or colonised by invertebrates such as sponges (41%) or sea anemones (15%). The changes in litter could be an indirect consequence of the receding sea ice, which opens the Arctic Ocean to the impacts of man's activities.

Alcohol dehydrogenase and aldehyde dehydrogenase gene polymorphisms, alcohol intake and the risk of colorectal cancer in the European Prospective Investigation into Cancer and Nutrition study

BACKGROUND/OBJECTIVES

Heavy alcohol drinking is a risk factor of colorectal cancer (CRC), but little is known on the effect of polymorphisms in the alcohol-metabolizing enzymes, alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) on the alcohol-related risk of CRC in Caucasian populations.

SUBJECTS/METHODS

A nested case-control study (1269 cases matched to 2107 controls by sex, age, study centre and date of blood collection) was conducted within the European Prospective Investigation into Cancer and Nutrition (EPIC) to evaluate the impact of rs1229984 (ADH1B), rs1573496 (ADH7) and rs441 (ALDH2) polymorphisms on CRC risk. Using the wild-type variant of each polymorphism as reference category, CRC risk estimates were calculated using conditional logistic regression, with adjustment for matching factors.

RESULTS

Individuals carrying one copy of the rs1229984(A) (ADH1B) allele (fast metabolizers) showed an average daily alcohol intake of 4.3 g per day lower than subjects with two copies of the rs1229984(G) allele (slow metabolizers) (P(diff)<0.01). None of the polymorphisms was associated with risk of CRC or cancers of the colon or rectum. Heavy alcohol intake was more strongly associated with CRC risk among carriers of the rs1573496(C) allele, with odds ratio equal to 2.13 (95% confidence interval: 1.26-3.59) compared with wild-type subjects with low alcohol consumption (P(interaction)=0.07).

CONCLUSIONS

The rs1229984(A) (ADH1B) allele was associated with a reduction in alcohol consumption. The rs1229984 (ADH1B), rs1573496 (ADH7) and rs441 (ALDH2) polymorphisms were not associated with CRC risk overall in Western-European populations. However, the relationship between alcohol and CRC risk might be modulated by the rs1573496 (ADH7) polymorphism.

Identification of gonadal tissue in cryptorchid stallion can be improved by molecular biological analysis - a case report

Surgically removed testicular tissue in cryptorchid stallions is sometimes difficult to identify because of morphological and histological malformation. Therefore, a sure method to characterise the removed tissue is required. A 2-year-old Haflinger stallion was castrated after diagnosis of cryptorchidism to remove the left intra-abdomnial testis. Intra-operative exploration of the abdominal cavity revealed a firm, dysmorphic structure, which could not be identified as testis based on macroscopic anatomy. The removed tissue was Bouin-fixed and paraffin-embedded for histological examination. We additionally applied immuno-histochemistry for smooth muscle actin to identify tubular structures as well as reverse transcriptase polymerase chain reaction (RT-PCR) to detect the expression of steroidogenic acute regulatory protein (StAR), indicating the presence of Leydig cells. A hCG test was conducted after surgery to screen for remaining testicular tissue. Histological examination using haematoxylin and eosin staining revealed signs of tissue calcification, amorph matrix with scattered cells and round structures. The latter could not be definitely identified as tubules. Actin staining revealed a few tubular wall structures. StAR mRNA expression indicated the presence of Leydig cells in parts of the removed tissue. The hCG test after castration showed no increase in testosterone. Histological and molecular biological examination of extirpated tissue in cryptorchid stallions can play an important role in the identification of the malformed testes like structures. The use of molecular biological techniques provides the opportunity to characterise surgically removed abdominal tissue that cannot be clearly diagnosed by routine histological examination.

The pluripotency factor LIN28 in monkey and human testes: a marker for spermatogonial stem cells?

Mammalian spermatogenesis is maintained by spermatogonial stem cells (SSCs). However, since evidentiary assays and unequivocal markers are still missing in non-human primates (NHPs) and man, the identity of primate SSCs is unknown. In contrast, in mice, germ cell transplantation studies have functionally demonstrated the presence of SSCs. LIN28 is an RNA-binding pluripotent stem cell factor, which is also strongly expressed in undifferentiated mouse spermatogonia. By contrast, two recent reports indicated that LIN28 is completely absent from adult human testes. Here, we analyzed LIN28 expression in marmoset monkey (Callithrix jacchus) and human testes during development and adulthood and compared it with that in mice. In the marmoset, LIN28 was strongly expressed in migratory primordial germ cells and gonocytes. Strikingly, we found a rare LIN28-positive subpopulation of spermatogonia also in adult marmoset testis. This was corroborated by western blotting and quantitative RT–PCR. Importantly, in contrast to previous publications, we found LIN28-positive spermatogonia also in normal adult human and additional adult NHP testes. Some seasonal breeders exhibit a degenerated (involuted) germinal epithelium consisting only of Sertoli cells and SSCs during their non-breeding season. The latter re-initiate spermatogenesis prior to the next breeding-season. Fully involuted testes from a seasonal hamster and NHP (Lemur catta) exhibited numerous LIN28-positive spermatogonia, indicating an SSC identity of the labeled cells. We conclude that LIN28 is differentially expressed in mouse and NHP spermatogonia and might be a marker for a rare SSC population in NHPs and man. Further characterization of the LIN28-positive population is required.

Semi-automated image analysis for the assessment of megafaunal densities at the Arctic deep-sea observatory HAUSGARTEN

Megafauna play an important role in benthic ecosystem function and are sensitive indicators of environmental change. Non-invasive monitoring of benthic communities can be accomplished by seafloor imaging. However, manual quantification of megafauna in images is labor-intensive and therefore, this organism size class is often neglected in ecosystem studies. Automated image analysis has been proposed as a possible approach to such analysis, but the heterogeneity of megafaunal communities poses a non-trivial challenge for such automated techniques. Here, the potential of a generalized object detection architecture, referred to as iSIS (intelligent Screening of underwater Image Sequences), for the quantification of a heterogenous group of megafauna taxa is investigated. The iSIS system is tuned for a particular image sequence (i.e. a transect) using a small subset of the images, in which megafauna taxa positions were previously marked by an expert. To investigate the potential of iSIS and compare its results with those obtained from human experts, a group of eight different taxa from one camera transect of seafloor images taken at the Arctic deep-sea observatory HAUSGARTEN is used. The results show that inter- and intra-observer agreements of human experts exhibit considerable variation between the species, with a similar degree of variation apparent in the automatically derived results obtained by iSIS. Whilst some taxa (e. g. Bathycrinus stalks, Kolga hyalina, small white sea anemone) were well detected by iSIS (i. e. overall Sensitivity: 87%, overall Positive Predictive Value: 67%), some taxa such as the small sea cucumber Elpidia heckeri remain challenging, for both human observers and iSIS.

Developmental expression of the pluripotency factor sal-like protein 4 in the monkey, human and mouse testis: restriction to premeiotic germ cells

SALL4 (sal-like protein 4) is a pluripotency transcription factor, which is highly expressed in embryonic stem (ES) cells and which is essential for mouse preimplantation development. In adult mouse organs, Sall4 mRNA is highly expressed in the testis and ovary, while there is only little or no expression in other organs. There is also a high expression of SALL4 in human testicular germ cell tumors. However, there is as yet no detailed analysis of SALL4 expression during mammalian testicular development. We analyzed SALL4 expression in ES cells, preimplantation embryos, and the developing and adult testis of a nonhuman primate (NHP) species, the common marmoset monkey (Callithrix jacchus). Immunofluorescence revealed SALL4 in the nuclei of marmoset ES cells and preimplantation embryos. Marmoset SALL4 isoform analysis in ES cells and newborn and adult testis by RT- PCR and Western blotting showed two different isoforms, SALL4-A and SALL4-B. Immunohistochemistry localized this transcription factor to the nuclei of primordial germ cells and most gonocytes in the prenatal and early postnatal marmoset testis. In the pubertal and adult testis SALL4 was present in undifferentiated spermatogonia. In the developing and adult human and mouse testis SALL4 expression mimicked the pattern in the marmoset. Adult testes from additional NHP species, the treeshrew, the cat and the dog also exhibited SALL4 in undifferentiated spermatogonia, indicating a conserved expression in the mammalian testis. Taking into account the importance of SALL4 for mouse development, we conclude that SALL4 may play an important role during mammalian germ cell development and is involved in the regulation of spermatogonial proliferation in the adult testis.

[Hypersensitivity to proton pump inhibitors]

Hypersensitivity to proton pump inhibitors (PPI) is rare but potentially severe. An increase in hypersensitivity reactions to PPI is expected as these drugs are widely prescribed and some have become available over-the-counter. Allergy to PPI has to be considered in patients presenting anaphylaxis, late-type skin rashes, interstitial nephritis and other organ involvement suspicious to be drug-induced. Cross-reactivity between PPI is of concern, as they are closely related in structure. Skin prick- and intradermal testing are reliable tools to confirm immediate-type allergy to one PPI compound and search for safe alternatives. We review the literature on immediate and delayed hypersensitivity to these drugs.

Presence of histone H3 acetylated at lysine 9 in male germ cells and its distribution pattern in the genome of human spermatozoa

During spermatogenesis, approximately 85% of histones are replaced by protamines. The remaining histones have been proposed to carry essential marks for the establishment of epigenetic information in the offspring. The aim of the present study was to analyse the expression pattern of histone H3 acetylated at lysine 9 (H3K9ac) during normal and impaired spermatogenesis and the binding pattern of H3K9ac to selected genes within ejaculates. Testicular biopsies, as well as semen samples, were used for immunohistochemistry. Chromatin immunoprecipitation was performed with ejaculated sperm chromatin. HeLa cells and prostate tissue served as controls. Binding of selected genes was evaluated by semiquantitative and real-time polymerase chain reaction. Immunohistochemistry of H3K9ac demonstrated positive signals in spermatogonia, spermatocytes, elongating spermatids and ejaculated spermatozoa of fertile and infertile men. H3K9ac was associated with gene promoters (CRAT, G6PD, MCF2L), exons (SOX2, GAPDH, STK11IP, FLNA, PLXNA3, SH3GLB2, CTSD) and intergenic regions (TH) in fertile men and revealed shifts of the distribution pattern in ejaculated spermatozoa of infertile men. In conclusion, H3K9ac is present in male germ cells and may play a role during the development of human spermatozoa. In addition, H3K9ac is associated with specific regions of the sperm genome defining an epigenetic code that may influence gene expression directly after fertilisation.

The Pararectus approach for anterior intrapelvic management of acetabular fractures

A new anterior intrapelvic approach for the surgical management of displaced acetabular fractures involving predominantly the anterior column and the quadrilateral plate is described. In order to establish five ‘windows’ for instrumentation, the extraperitoneal space is entered along the lateral border of the rectus abdominis muscle. This is the so-called ‘Pararectus’ approach. The feasibility of safe dissection and optimal instrumentation of the pelvis was assessed in five cadavers (ten hemipelves) before implementation in a series of 20 patients with a mean age of 59 years (17 to 90), of whom 17 were male. The clinical evaluation was undertaken between December 2009 and December 2010. The quality of reduction was assessed with post-operative CT scans and the occurrence of intra-operative complications was noted. In cadavers, sufficient extraperitoneal access and safe instrumentation of the pelvis were accomplished. In the patients, there was a statistically significant improvement in the reduction of the fracture (pre- versus post-operative: mean step-off 3.3 mm (sd 2.6) vs 0.1 mm (sd 0.3), p < 0.001; and mean gap 11.5 mm (sd 6.5) vs 0.8 mm (sd 1.3), p < 0.001). Lesions to the peritoneum were noted in two patients and minor vascular damage was noted in a further two patients. Multi-directional screw placement and various plate configurations were feasible in cadavers without significant retraction of soft tissues.

In the treatment of acetabular fractures predominantly involving the anterior column and the quadrilateral plate, the Pararectus approach allowed anatomical restoration with minimal morbidity related to the surgical access.

Connexin 43: its regulatory role in testicular junction dynamics and spermatogenesis

Spermatogenesis is an intensely regulated process of germ cell development which takes place in the seminiferous tubules of the testis. In addition to known endocrine and autocrine/paracrine signaling pathways, there is now strong evidence that direct intercellular communication via gap junction channels and their specific connexins represents an important mechanism in the regulation of spermatogenesis. Another possibility is that connexins may indirectly regulate the spermatogenic process through modulation of tight and adherens junction proteins, further main structural components of the Sertoli-Sertoli junctional complexes at the blood-testis barrier site. The present review is focused on connexin 43 and updates its possible roles and functions in testicular junction dynamics and in the initiation and maintenance of spermatogenesis. In addition, testicular phenotypes of recently generated (1) conventional connexin 43 knockout mice, (2) connexin 43 knockin mice and (3) transgenic mice exhibiting a cell-specific (conditional) connexin 43 knockout will be discussed.

The Sda/GM2-glycan is a carbohydrate marker of porcine primordial germ cells and of a subpopulation of spermatogonia in cattle, pigs, horses and llama

Spermatogonia are a potential source of adult pluripotent stem cells and can be used for testis germ cell transplantation. Markers for the isolation of these cells are of great importance for biomedical applications. Primordial germ cells and prepubertal spermatogonia in many species can be identified by their binding of Dolichos biflorus agglutinin (DBA). This lectin binds to two different types of glycans, which are α-linked N-acetylgalactosamine (GalNac) and β-linked GalNac, if this is part of the Sda or GM2 glycotopes. We used the MAB CT1, which is specific for the trisaccharides motif NeuAcα2-3(GalNAcβ1-4)Galβ1-, which is common to both Sda and GM2 glycotopes, to further define the glycosylation of DBA binding germ cells. In porcine embryos, CT1 bound to migratory germ cells and gonocytes. CT1/DBA double staining showed that the mesonephros was CT1 negative but contained DBA-positive cells. Gonocytes in the female gonad became CT1 negative, while male gonocytes remained CT1 positive. In immunohistological double staining of cattle, pig, horse and llama testis, DBA and CT1 staining was generally colocalised in a subpopulation of spermatogonia. These spermatogonia were mainly single, sometimes paired or formed chains of up to four cells. Our data show that the Sda/GM2 glycotope is present in developing germ cells and spermatogonia in several species. Owing to the narrower specificity of the CT1 antibody, compared with DBA, the former is likely to be a useful tool for labelling and isolation of these cells.