Spermatogenesis and related plasma androgen levels in Atlantic halibut (Hippoglossus hippoglossus L.)

Spermatogenesis in male Atlantic halibut (Hippoglossus hippoglossus L.) was investigated by sampling blood plasma and testicular tissue from 15-39-month-old fish. The experiment covered a period in which all fish reached puberty and completed sexual maturation at least once. The germinal compartment in Atlantic halibut testis appears to be organized in branching lobules of the unrestricted spermatogonial type, because spermatocysts with spermatogonia were found throughout the testis. Spermatogenesis was characterized histologically, and staged according to the most advanced type of germ cell present: spermatogonia (Stage I), spermatogonia and spermatocytes (Stage II), spermatogonia, spermatocytes and spermatids (Stage III), spermatogonia, spermatocytes, spermatids and spermatozoa (Stage IV), and regressing testis (Stage V). Three phases could be distinguished: first, an initial phase with low levels of circulating testosterone (T; quantified by RIA) and 11-ketotestosterone (11-KT; quantified by ELISA), spermatogonial proliferation, and subsequently the initiation of meiosis marked by the formation of spermatocytes (Stage I and II). Secondly, a phase with increasing T and 11-KT levels and with haploid germ cells including spermatozoa present in the testis (Stage III and IV). Thirdly, a phase with low T and 11-KT levels and a regressing testis with Sertoli cells displaying signs of phagocytotic activity (Stage V). Circulating levels of 11-KT were at least four-fold higher than those of T during all stages of spermatogenesis. Increasing plasma levels of T and 11-KT were associated with increasing testicular mass throughout the reproductive cycle. The absolute level of, or the relation between, testis growth and circulating androgens were not significantly different in first time spawners compared to fish that underwent their second spawning season. These results provide reference levels for Atlantic halibut spermatogenesis.     

Cyanobacterial diversity in geographically related and distant host plants of the genus Gunnera

The diversity among 45 cyanobacterial isolates from 11 different Gunnera species originating from different geographical areas was examined. By means of polymerase chain reaction (PCR) fingerprinting with short tandemly repeated repetitive (STRR) sequences as primers, ten groups of symbiotic cyanobacteria and five unique isolates not belonging to a particular group were identified. Most groups were restricted to one geographical area, indicating a limited distribution of related cyanobacterial strains. An extensive cyanobacterial diversity was found both within and between the 11 different Gunnera species. Within a particular plant and even within the same stem gland, more than one cyanobacterial strain at a time could be present. These results indicate a low specificity in Gunnera-Nostoc symbiosis.     

Simian Y Chromosomes: species-specific rearrangements of DAZ, RBM, and TSPY versus contiguity of PAR and SRY

The three human male specific expressed gene families DAZ, RBM, and TSPY are known to be repetitively clustered in the Y-specific region of the human Y Chromosome (Chr). RBM and TSPY are Y-specifically conserved in simians, whereas DAZ cannot be detected on the Y chromosomes of New World monkeys. The proximity of SRY to the pseudoautosomal region (PAR) is highly conserved and thus most effectively stabilizes the pseudoautosomal boundary on the Y (PABY) in simians. In contrast, the non-recombining part of the Y Chrs, including DAZ, RBM, and TSPY, was exposed to species-specific amplifications, diversifications, and rearrangements. Evolutionary fast fixation of any of these variations was possible as long as they did not interfere with male fertility. Received: 18 August 1997 / Accepted: 13 November 1997     

A Revised Time Tree of the Asterids: Establishing a Temporal Framework For Evolutionary Studies of the Coffee Family (Rubiaceae)

Divergence time analyses in the coffee family (Rubiaceae) have all relied on the same Gentianales crown group age estimate, reported by an earlier analysis of the asterids, for defining the upper age bound of the root node in their analyses. However, not only did the asterid analysis suffer from several analytical shortcomings, but the estimate itself has been used in highly inconsistent ways in these Rubiaceae analyses. Based on the original data, we here reanalyze the divergence times of the asterids using relaxed-clock models and 14 fossil-based minimum age constraints. We also expand the data set to include an additional 67 taxa from Rubiaceae sampled across all three subfamilies recognized in the family. Three analyses are conducted: a separate analysis of the asterids, which completely mirrors the original asterid analysis in terms of taxon sample and data; a separate analysis of the Gentianales, where the result from the first analysis is used for defining a secondary root calibration point; and a combined analysis where all taxa are analyzed simultaneously. Results are presented in the form of a time-calibrated phylogeny, and age estimates for asterid groups, Gentianales, and major groups of Rubiaceae are compared and discussed in relation to previously published estimates. Our updated age estimates for major groups of Rubiaceae provide a significant step forward towards the long term goal of establishing a robust temporal framework for the divergence of this biologically diverse and fascinating group of plants.     

BCG Skin Infection Triggers IL-1R-MyD88-Dependent Migration of EpCAMlow CD11bhigh Skin Dendritic cells to Draining Lymph Node During CD4+ T-Cell Priming

The transport of antigen from the periphery to the draining lymph node (DLN) is critical for T-cell priming but remains poorly studied during infection with Mycobacterium bovis Bacille Calmette-Guérin (BCG). To address this we employed a mouse model to track the traffic of Dendritic cells (DCs) and mycobacteria from the BCG inoculation site in the skin to the DLN. Detection of BCG in the DLN was concomitant with the priming of antigen-specific CD4⁺ T cells at that site. We found EpCAM^low CD11b^high migratory skin DCs to be mobilized during the transport of BCG to the DLN. Migratory skin DCs distributed to the T-cell area of the LN, co-localized with BCG and were found in close apposition to antigen-specific CD4⁺ T cells. Consequently, blockade of skin DC traffic into DLN dramatically reduced mycobacterial entry into DLN and muted T-cell priming. Interestingly, DC and mycobacterial entry into the DLN was dependent on IL-1R-I, MyD88, TNFR-I and IL-12p40. In addition, we found using DC adoptive transfers that the requirement for MyD88 in BCG-triggered migration was not restricted to the migrating DC itself and that hematopoietic expression of MyD88 was needed in part for full-fledged migration. Our observations thus identify a population of DCs that contribute towards the priming of CD4⁺ T cells to BCG infection by transporting bacilli into the DLN in an IL-1R-MyD88-dependent manner and reveal both DC-intrinsic and -extrinsic requirements for MyD88 in DC migration.     

Views of Swedish Commissioning Parents Relating to the Exploitation Discourse in Using Transnational Surrogacy

Transnational surrogacy, when people travel abroad for reproduction with the help of a surrogate mother, is a heavily debated phenomenon. One of the most salient discourses on surrogacy is the one affirming that Westerners, in their quest for having a child, exploit poor women in countries such as India. As surrogacy within the Swedish health care system is not permitted, Swedish commissioning parents have used transnational surrogacy, and the majority has turned to India. This interview study aimed to explore how commissioning parents negotiate the present discourses on surrogacy. Findings from the study suggest that the commissioning parents’ views on using surrogacy are influenced by competing discourses on surrogacy represented by media and surrogacy agencies. The use of this reproductive method resulted, then, in some ambiguity. Although commissioning parents defy the exploitation discourse by referring to what they have learnt about the surrogate mother’s life situation and by pointing at the significant benefits for her, they still had a request for regulation of surrogacy in Sweden, to better protect all parties involved. This study, then, gives a complex view on surrogacy, where the commissioning parents simultaneously argue against the exploitation discourse but at the same time are uncertain if the surrogate mothers are well protected in the surrogacy arrangements. Their responses to the situation endorse the need for regulation both in Sweden and India.