Sperm storage in the vertebrate female reproductive tract: How does it work so well?

The capacity for sperm storage within the female reproductive tract occurs widely across all groups of vertebrate species and is exceptionally well developed in some reptiles (maximum duration, 7 yr) and fish (maximum duration, >1 yr). Amphibians (most salamanders and one species of frog; duration approximately 5 mo), all birds examined to date and some bats, have also evolved the ability to store spermatozoa in the female reproductive tract. Although there are many reports on both the occurrence of female sperm storage and its adaptive benefits, few studies have been directed toward explaining the mechanisms involved. Phylogenetic evidence suggests that the capacity for sperm storage has evolved independently within different taxonomic groups, and it is by no means clear whether these groups have established similar or different mechanisms or whether simple and common principles have been exploited during evolution. If the process has indeed developed by the invention of numerous different and species-specific mechanisms, it is surprising that none have yet been elucidated by technologists wishing to improve the long-term storage of fresh semen. On the other hand, if there is a simple and common solution to the problem, readily accessed by diverse groups of species, it is equally logical to suppose that the mechanism should be easily discovered in the laboratory. While recognizing that studies on wild species are usually neither practically or ethically easy to undertake, it is clear that there is a huge and largely unexplored field to be investigated.     

Synthesis of pyrrolo[3,2-h]quinolinones with good photochemotherapeutic activity and no DNA damage

In the search for new photochemotherapeutic agents, a series of derivatives of the ring system pyrrolo[3,2-h]quinoline—bioisosters of the angular furocoumarin angelicin—were synthesized through a four-step synthetic approach, in reasonable overall yields. Eight of the synthesized derivatives showed a remarkable phototoxicity against a panel of four human tumor cell lines and a great dose UV-A dependence, reaching IC₅₀ values at submicromolar level. The mode of cellular death photoinduced by pyrrolo[3,2-h]quinolines was evaluated through a series of flow cytometric analysis and other tests were performed to clarify their mechanism of action.     

Nanodiamond bullets and their biological targets

The potential of nanodiamond bullets for use in ballistic delivery of biologically active molecules was investigated. Detonation nanodiamond particles were coated with DNA, synthetic ethylene precursor, or ethylene antagonist or were labeled with fluorescent dyes and delivered into bacteria, yeast, insect cells, and plant tissues with the help of a Bio-Rad particle delivery system PDS-1000/He. Detonation nanodiamonds are both mechanically and chemically stable and can be used as DNA carriers for biolistic transformation of cells and in delivery of biologically active molecules.     

Ultrastructural characterization of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid-induced cell death in embryonic dopaminergic neurons

Developing neuronal populations undergo significant attrition by natural cell death. Dopaminergic neurons in the substantia nigra pars compacta undergo apoptosis during synaptogenesis. Following this time window, destruction of the anatomic target of dopaminergic neurons results in dopaminergic cell death but the morphology is no longer apoptotic. We describe ultrastructural changes that appear unique to dying embryonic dopaminergic neurons. In primary cultures of mesencephalon, death of dopaminergic neurons is triggered by activation of glutamate receptors sensitive to alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), and differs ultrastructurally from both neuronal apoptosis or typical excitotoxicity. AMPA causes morphological changes selectively in dopaminergic neurons, without affecting other neurons in the same culture dishes. Two hours after the onset of treatment swelling of Golgi complexes is apparent. At 3 h, dopaminergic neurons display loss of membrane asymmetry (coinciding with commitment to die), as well as nuclear membrane invagination, irregular aggregation of chromatin, and mitochondrial swelling. Nuclear changes continue to worsen until loss of cytoplasmic structures and cell death begins to occur after 12 h. These changes are different from those described in neurons undergoing either apoptosis or excitotoxic death, but are similar to ultrastructural changes observed in spontaneous death of dopaminergic neurons in the natural mutant weaver mouse.     

Potentiation of lipopolysaccharide-induced IL-6 release by uridine triphosphate in macrophages: Cross-interaction with cyclooxygenase-2-dependent prostaglandin E2 production

Our previous study has demonstrated the potentiation by uridine triphosphate (UTP) of nitric oxide (NO) and prostaglandin E₂ (PGE₂) production in lipopolysaccharide (LPS)-stimulated murine J774 macrophages. In this study, we found that the amount of interleukin-6 (IL-6) release in response to LPS stimulation was greatly enhanced in the presence of UTP. This enhancement exhibited concentration dependence and occurred after 8 h of treatment with LPS. RT-PCR analysis indicated that the steady-state level of IL-6 mRNA induced by LPS was apparently increased upon co-addition of UTP. The potentiation by UTP was inhibited by the treatment with U73122 (a phosphatidylinositol-phospholipase C inhibitor), BAPTA/AM (an intracellular Ca²⁺ chelator), KN-93 (a selective inhibitor of calmodulin-dependent protein kinase) or PDTC (a nuclear factor B inhibitor). To understand the cross-regulation among NO, PGE₂ and IL-6, all of which are dramatically induced after LPS stimulation, the effects of L-NAME (a nitric oxide synthase inhibitor), indomethacin (a cyclooxygenase inhibitor), NS-398 (a cycloxygenase-2 inhibitor) and IL-6 antibody were tested. The results revealed the positive regulation between PGE₂ and IL-6 synthesis because NS-398 and indomethacin inhibited LPS plus UTP-induced IL-6 release, and IL-6 antibody attenuated LPS plus UTP-induced PGE₂ release. Taken together these results reinforce the role of UTP as a regulatory element in inflamed sites by demonstrating the capacity of this nucleotide to potentiate LPS-induced release of inflammatory mediators.     

A New Aspect in Glycolipid Biology: Glycosphingolipids as Antigens Recognized by T Lymphocytes

T cells may recognize a large variety of ligands with different chemical structures. Recently, glycosphingolipids have also been shown to stimulate human T lymphocytes. Recognition of glycosphingolipids is restricted by the nonpolymorphic CD1 molecules, expressed by professional antigen-presenting cells and by macrophages infiltrating inflammatory sites. CD1 molecules have a structure resembling that of classical MHC class I molecules, with the terminal extracellular domains characterized by two antiparallel a helices placed on two hydrophobic pockets. The glycosphingolipids bound to CD1 insert the lipid tails in the two pockets and position the hydrophilic head on the external part of CD1. The TCR interacts with aminoacids present in the two a helices and with residues provided by the carbohydrate moiety of glycosphingolipids and discriminates their structural variations. T cells recognizing self-glycosphingolipids release proinflammatory cytokines and may have a pathogenetic role in autoimmune diseases such as multiple sclerosis.