Increased apoptosis occurring during the first wave of spermatogenesis is stage-specific and primarily affects midpachytene spermatocytes in the rat testis

The physiological apoptosis that occurs in immature testis appears to be necessary for the maturation of this tissue. Thus, inhibition of the early apoptotic wave associated with the first round of spermatogenesis is followed by accumulation of spermatogonia and infertility later in life. To identify the cell types undergoing apoptosis in immature rat testis and to characterize the relationship between this apoptosis and progression of the first wave of spermatogenesis, sequential viable segments of seminiferous tubules from 8-, 18-, and 26-day-old rats were examined under a phase-contrast microscope. One novel observation was the existence of pronounced stage-specificity during the peak of apoptosis at the very early postnatal ages of 18 and 26 days. Increased apoptosis of pachytene spermatocytes in stages VII-VIII was the major feature that distinguished immature spermatogenesis from the corresponding adult process. The frequency of apoptosis among type A spermatogonia in immature stages IX-I was also elevated in comparison to the corresponding mature stages. The age-related peak of apoptosis was mediated by caspase 3; furthermore, stage-dependent expression of Bax in midpachytene spermatocytes was observed in the 18- and 26-day-old testis. These observations suggest that this Bax-regulated, caspase 3-mediated, increased apoptosis of midpachytene spermatocytes during the first wave of immature spermatogenesis represents a major difference in comparison to apoptosis occurring in the mature testis, and it may play an important regulatory role in establishing spermatogenesis in the rat testis.     

The participation of CCK-8-ergic mechanisms in the regulation of emotional behavior in rodents

Effects of CCK-8 receptor agonists caerulein and pentagastrin and CCK-8 receptor antagonist proglumide on exploratory and locomotor activity of mice and rats were studied. Systemic administration of caerulein (500 ng/kg 1 mcg/kg) decreased significantly the exploratory activity of mice in elevated plus-maze. This anxiogenic-like action of caerulein was attenuated by acute pretreatment with proglumide (1 and 15 mg/kg) but not with diazepam (up to 0.75 mg/kg). Proglumide slightly increased the exploratory activity of rats in plus-maze; on the other hand, caerulein and pentagastrin potently decreased the measures of exploration in this test. Caerulein (10-100 mcg/kg) and proglumide (1 and 15 mg/kg) inhibited 3H-pentagastrin binding in mice brain in in vivo experiments. The data obtained indicate that CCK-8-ergic mechanisms in brain play an important role in the generation of anxiety states in rodents.     

Polarized THG Microscopy Identifies Compositionally Different Lipid Droplets in Mammalian Cells

Cells store excess lipids as two major compounds, triacylglycerols (TAGs) and cholesteryl esters (CEs), inside lipid droplets (LDs). The degree of lipid ordering is considered to play a major role in the mobility and enzymatic processing of lipids in LDs. Here, we provide evidence that polarized third-harmonic generation (THG) microscopy distinguishes between native TAG- and CE-enriched LDs in cells due to the different ordering of the two lipid species. We first demonstrate that the responses from synthetic TAG- and CE-enriched LDs using THG microscopy with linear and circular polarizations differ according to their different intrinsic ordering. We then employ simulations to dissect how polarization effects influence the THG from an isotropic LD. Finally, we induce TAG- and CE-enriched LDs in murine macrophages and demonstrate that polarized THG responses increase in a nonlinear fashion with increasing CE/TAG ratio. This suggests that with an increasing CE content, there is a rather sharp transition toward increased LD ordering. Our results demonstrate that polarized THG microscopy enables label-free quantitative analysis of LD ordering and discriminates between compositionally different LDs in intact mammalian cells.     

A 3-year exposure to CO2 and O3 induced minor changes in soil N cycling in a meadow ecosystem

We investigated the individual and interactive effects of moderately elevated CO₂ (ambient air + 100 ppm) and/or O₃ (40–50 ppb) on soil N cycling and microbial biomass N in a 3-year open-top chamber experiment conducted in meadow mesocosms. The results show that elevated O₃ decreased the concentrations of mineral N and NH₄⁺-N in the mesocosm soil in the last growing season (2004). Total N, NO₃⁻-N, microbial biomass N, decomposition rate, potential nitrification and denitrification were not affected by elevated O₃ and/or CO₂. It is thus concluded that the proposed future ambient O₃ and CO₂ levels, such as used in this experiment, may not induce major changes in the below-ground N processes in N-poor northern European hay meadow ecosystems.     

Effects of polarization in the presence and absence of biocides on biofilms in a simulated paper machine water

The antifouling potential of electric polarization combined and not combined with biocides was studied in nonsaline warm water with high organic content. Deinococcus geothermalis is a bacterium known for forming colored biofilms in paper machines and for its persistence against cleaning and chemical treatments. When D. geothermalis biofilms grown for 24 h in simulated paper machine water were exposed to cathodic or cathodically weighted pulsed polarization at least 60% (P < 0.05) of the biofilms were removed from stainless steel (AISI 316L). Biofilm removal by 25 ppm (effective substances 5-25 ppm) of oxidizing biocides (bromochloro-5,5-dimethylhydantoin, 2,2-dibromo-2-cyanoacetamide, peracetic acid) increased to 70% when combined with cathodically weighted pulsed polarization. Using a novel instrument that allows real-time detection of reactive oxygen species (ROS) we showed that the polarization program effective in antifouling generated ROS in a pulsed manner on the steel surface. We thus suggest that the observed added value of oxidative biocides combined with polarization depended on ROS. This suggestion was supported by the finding that a reductive biocide, methylene bisthiocyanate, counteracted the antifouling effect of polarization.     

Neurturin, RET, GFRα-1 and GFRα-2, but not GFRα-3, mRNA are expressed in mice gonads

The gonads are known to produce numerous hormones and also neurotrophins and their receptors. Here we demonstrate expression of glial-cell-line-derived neurotrophic factor (GDNF) family ligands and related receptors in adult mice gonads by in situ hybridization. GDNF mRNA was expressed in the ovary, but was not detectable in testis. Neurturin (NTN), another ligand in this family, gave rise to strong mRNA hybridization signals in a mosaic pattern in the seminiferous tubules of the testis at stages IX-XII and I-II of the cycle. NTN mRNA signals were also found in uterus and the oviduct. In testis, the transducing receptor RET as well as GDNF receptor alpha-1 (GFR)alpha-1 and GFRalpha-2 were distributed in complementary and overlapping patterns, the former at stages XI-XII-I and the latter at stages VII and VIII. GFRalpha-3 could not be detected. Expression of these trophic molecules suggests involvement of GDNF family ligands and related receptor components in reproduction.     

Separation of nearly identical repeats in shotgun assemblies using defined nucleotide positions, DNPs

An increasingly important problem in genome sequencing is the failure of the commonly used shotgun assembly programs to correctly assemble repetitive sequences. The assembly of non-repetitive regions or regions containing repeats considerably shorter than the average read length is in practice easy to solve, while longer repeats have been a difficult problem. We here present a statistical method to separate arbitrarily long, almost identical repeats, which makes it possible to correctly assemble complex repetitive sequence regions. The differences between repeat units may be as low as 1% and the sequencing error may be up to ten times higher. The method is based on the realization that a comparison of only a part of all overlapping sequences at a time in a data set does not generate enough information for a conclusive analysis. Our method uses optimal multi-alignments consisting of all the overlaps of each read. This makes it possible to determine defined nucleotide positions, DNPs, which constitute the differences between the repeat units. Differences between repeats are distinguished from sequencing errors using statistical methods, where the probabilities of obtaining certain combinations of candidate DNPs are calculated using the information from the multi-alignments. The use of DNPs and combinations of DNPs will allow for optimal and rapid assemblies of repeated regions. This method can solve repeats that differ in only two positions in a read length, which is the theoretical limit for repeat separation. We predict that this method will be highly useful in shotgun sequencing in the future.     

Effects of group size and pine defence chemicals on Diprionid sawfly survival against ant predation

The defence chemicals and behavioural adaptations (gregariousness and active defensive behaviour) of pine sawfly larvae may be effective against ant predation. However, previous studies have tested their defences against very few species of ants, and few experiments have explored ant predation in nature. We studied how larval group size (groups of 5 and 20 in Neodiprion sertifer and 10, 20 and 40 in Diprion pini) and variation in levels of defence chemicals in the host tree (Scots pine, Pinus sylvestris) affect the survival of sawfly larvae. Food preference experiments showed that ants do eat sawfly larvae, although they are not their most preferred food item. According to our results, ant predation significantly increases the mortality rate of sawfly larvae. Larval mortality was minor on pine tree branches where ant traffic was excluded. We also found that a high resin acid concentration in the host tree significantly decreased the mortality of D. pini larvae when ants were present. However, there was no such relationship between the chemical concentrations of the host tree and larval mortality for N. sertifer. Surprisingly, grouping did not help sawfly larvae against ant predation. Mortality risk was the same for all group sizes. The results of the study seemingly contradict previous understanding of the effectiveness of defence mechanisms of pine sawfly against ant predation, and suggest that ants (Formica exsecta in particular) are effective predators of sawfly larvae.An erratum to this article can be found at