Preliminary experience with subcutaneous human ovarian cortex transplantation in the NOD-SCID mouse.

Xenogeneic transplantation of ovarian cortex into an immunodeficient animal host may be an approach toward fertility preservation for young female patients undergoing cancer therapy. Our objective was to evaluate the development of follicles in human ovarian cortex placed s.c. in non-obese diabetic-severe combined immune deficiency (NOD-SCID) mice (n = 54). The following variables were compared: 1) male versus female mice as hosts, 2) intact versus pituitary down-regulated mice, and 3) warm versus cold tissue transport. After 2 wk, 37 of 50 (74%) of the human xenografts contained follicles. At 12 wk after transplantation, exogenous gonadotropin stimulation resulted in follicle growth in 19 of 37 (51%) of the grafts, including the development of antral follicles, which could be palpated and visualized through the mouse skin. Significantly more developing follicles were identified in male versus female mice (13 of 17 vs. 6 of 20, respectively; p = 0.013) after stimulation. No difference was found between intact and pituitary down-regulated mice as hosts. Follicular survival was significantly increased by warm versus cold tissue transport. Our results suggest that s.c. ovarian cortex xenografting into NOD-SCID mice is feasible. Primordial follicles in ovarian xenografts retain their developmental potential and form antral follicles following gonadotropin stimulation.     

Short-Term Summer Inundation as a Measure to Counteract Acidification in Rich Fens

In regions with intensive agriculture, water level fluctuation in wetlands has generally become constricted within narrow limits. Water authorities are, however, considering the re-establishment of fluctuating water levels as a management tool in biodiverse, base-rich fens (‘rich fens’). This includes temporary inundation with surface water from ditches, which may play an important role in counteracting acidification in order to conserve and restore biodiversity. Inundation may result in an increased acid neutralizing capacity (ANC) for two reasons: infiltration of base-rich inundation water into peat soils, and microbial alkalinity generation under anaerobic conditions. The main objectives of this study were to test whether short-term (2 weeks) summer inundation is more effective than short-term winter inundation to restore the ANC in the upper 10 cm of non-floating peat soils, and to explain potential differences. Large-scale field experiments were conducted for five years in base-rich fens and Sphagnum-dominated poor fens. Winter inundation did not result in increased porewater ANC, because infiltration was inhibited in the waterlogged peat and evapotranspiration rates were relatively low. Also, low temperatures limit microbial alkalinity generation. In summer, however, when temperature and evapotranspiration rates are higher, inundation resulted in increased porewater Ca and HCO₃ ^- concentrations, but only in areas with characteristic rich fen bryophytes. This increase was not only due to stronger infiltration into the soil, but also to higher microbial alkalinity generation under anaerobic conditions. In contrast, porewater ANC did not increase in Sphagnum-plots as a result of the ability of Sphagnum spp. to acidify their environment. In both rich and poor fens, flooding-induced P-mobilization remained sufficiently low to safeguard P-limited vegetation. NO₃ ^- and NH₄ ⁺ dynamics showed no considerable changes either. In conclusion, short-term summer inundation with base-rich and nutrient-poor surface water is considered beneficial in the management of non-floating rich fens, and much more effective than winter inundation.     

Selectivity of the surface binding site (SBS) on barley starch synthase I

Starch synthase I (SSI) from various sources has been shown to preferentially elongate branch chains of degree of polymerisation (DP) from 6–7 to produce chains of DP 8–12. In the recently determined crystal structure of barley starch synthase I (HvSSI) a so-called surface binding site (SBS) was seen, which was found by mutational analysis to be essential for the activity of HvSSI on glycogen. We now show in binding studies using surface plasmon resonance that HvSSI has no detectable affinity for malto-triose and -tetraose, but clearly binds maltopentaose, -hexaose, -heptaose (M7) and β-cyclodextrin (β-CD) albeit with a measurable K _D for only β-CD and M7. Moreover, an HvSSI SBS mutant F538A lost the ability to bind β-CD and maltooligosaccharides. This behaviour suggests that a chain in the α-glucan molecule (amylopectin) that is undergoing extension attaches itself at the SBS and that the active site itself, likely working on a different end chain, has low affinity for both substrate and product.     

Mismatch between fishway operation and timing of fish movements: a risk for cascading effects in partial migration systems

Habitat fragmentation is a growing problem worldwide. Particularly in river systems, numerous dams and weirs hamper the movement of a wide variety of species. With the aim to preserve connectivity for fish, many barriers in river systems are equipped with fishways (also called fish passages or fish ladders). However, few fishways provide full connectivity. Here we hypothesized that restricted seasonal opening times of fishways can importantly reduce their effectiveness by interfering with the timing of fish migration, for both spring‐ and autumn‐spawning species. We empirically tested our hypothesis, and discuss the possible eco‐evolutionary consequences of affected migration timing. We analyzed movements of two salmonid fishes, spring‐spawning European grayling (Thymallus thymallus) and autumn‐spawning brown trout (Salmo trutta), in Norway's two largest river systems. We compared their timing of upstream passage through four fishways collected over 28 years with the timing of fish movements in unfragmented river sections as monitored by radiotelemetry. Confirming our hypothesis, late opening of fishways delayed the migration of European grayling in spring, and early closure of fishways blocked migration for brown trout on their way to spawning locations during late autumn. We show in a theoretical framework how restricted opening times of fishways can induce shifts from migratory to resident behavior in potamodromous partial migration systems, and propose that this can induce density‐dependent effects among fish accumulating in lower regions of rivers. Hence, fragmentation may not only directly affect the migratory individuals in the population, but may also have effects that cascade downstream and alter circumstances for resident fish. Fishway functionality is inadequate if there is a mismatch between natural fish movements and fishway opening times in the same river system, with ecological and possibly evolutionary consequences for fish populations.     

Comparative assessment of the thermal tolerance of spotted stemborer,Chilo partellus (Lepidoptera: Crambidae) and its larval parasitoid,Cotesia sesamiae (Hymenoptera: Braconidae)

Under stressful thermal environments, insects adjust their behavior and physiology to maintain key life‐history activities and improve survival. For interacting species, mutual or antagonistic, thermal stress may affect the participants in differing ways, which may then affect the outcome of the ecological relationship. In agroecosystems, this may be the fate of relationships between insect pests and their antagonistic parasitoids under acute and chronic thermal variability. Against this background, we investigated the thermal tolerance of different developmental stages of Chilo partellus Swinhoe (Lepidoptera: Crambidae) and its larval parasitoid, Cotesia sesamiae Cameron (Hymenoptera: Braconidae) using both dynamic and static protocols. When exposed for 2 h to a static temperature, lower lethal temperatures ranged from ?9 to 6 °C, ?14 to ?2 °C, and ?1 to 4 °C while upper lethal temperatures ranged from 37 to 48 °C, 41 to 49 °C, and 36 to 39 °C for C. partellus eggs, larvae, and C. sesamiae adults, respectively. Faster heating rates improved critical thermal maxima (CT_max) in C. partellus larvae and adult C. partellus and C. sesamiae. Lower cooling rates improved critical thermal minima (CT_min) in C. partellus and C. sesamiae adults while compromising CT_min in C. partellus larvae. The mean supercooling points (SCPs) for C. partellus larvae, pupae, and adults were ?11.82 ± 1.78, ?10.43 ± 1.73 and ?15.75 ± 2.47, respectively. Heat knock‐down time (HKDT) and chill‐coma recovery time (CCRT) varied significantly between C. partellus larvae and adults. Larvae had higher HKDT than adults, while the latter recovered significantly faster following chill‐coma. Current results suggest developmental stage differences in C. partellus thermal tolerance (with respect to lethal temperatures and critical thermal limits) and a compromised temperature tolerance of parasitoid C. sesamiae relative to its host, suggesting potential asynchrony between host–parasitoid population phenology and consequently biocontrol efficacy under global change. These results have broad implications to biological pest management insect–natural enemy interactions under rapidly changing thermal environments.     

More fibrosis and thrombotic complications but similar expression patterns of markers for coagulation and inflammation in symptomatic plaques from DM2 patients.

OBJECTIVE: One of the possible pathological mechanisms behind the increased vascular injury in diabetes mellitus type 2 (DM2) is the formation of advanced glycation end products (AGEs). The aim of this study was to investigate whether the presence of AGEs and specific markers for coagulation and inflammation in symptomatic atherosclerotic plaques from DM2 patients differs from plaques from nondiabetics. METHODS AND RESULTS: Carotid atherectomies were obtained from DM2 patients (n=11) and controls without DM2 matched for age and other cardiovascular risk factors (n=12) who were treated for symptomatic carotid artery stenosis. Plaques were graded according to the American Heart Association classification of lesions. More fibrosis and more thrombotic complications (p=0.007) were observed in carotid atherectomies from DM2 patients. Percentages of immunostained smooth muscle cells and macrophages in the lesions, quantified planimetrically, did not differ between the two groups. No differences were found in the immunostaining for T cells, tissue factor (TF), endothelial protein C receptor (EPCR), nuclear factor kappaB, and the AGE carboxymethyllysine. CONCLUSIONS: These findings demonstrate that DM2 is associated with increased plaque complications; however, a local changed presence of AGEs, TF, and EPCR seems not to be involved in this end stage of atherosclerosis.     

Glyoxalase-1 overexpression partially prevents diabetes-induced impaired arteriogenesis in a rat hindlimb ligation model

We hypothesize that diabetes-induced impaired collateral formation after a hindlimb ligation in rats is in part caused by intracellular glycation and that overexpression of glyoxalase-I (GLO-I), i.e. the major detoxifying enzyme for advanced-glycation-endproduct (AGE) precursors, can prevent this. Wild-type and GLO-I transgenic rats with or without diabetes (induced by 55 mg/kg streptozotocin) were subjected to ligation of the right femoral artery. Laser Doppler perfusion imaging showed a significantly decreased blood perfusion recovery after 6 days in the diabetic animals compared with control animals, without any effect of Glo1 overexpression. In vivo time-of-flight magnetic resonance angiography at 7-Tesla showed a significant decrease in the number and volume of collaterals in the wild-type diabetic animals compared with the control animals. Glo1 overexpression partially prevented this decrease in the diabetic animals. Diabetes-induced impairment of arteriogenic adaptation can be partially rescued by overexpressing of GLO-I, indicating a role of AGEs in diabetes-induced impaired collateral formation.     

General control of amino acid biosynthesis in mutants of Candida spec. EH 15/D

The general control of amino acid biosynthesis was investigated in Candida spec. EH 15/D, using single and double mutant auxotrophic strains and prototrophic revertants starved for their required amino acids. These experiments show that starvation for lysine, histidine, arginine, leucine, threonine, proline, serine, methionine, homoserine, asparagine, glutamic acid or aspartic acid can result in derepression of enzymes. A correlation was found between the degree of derepression, growth of strains, and concentration of required amino acids. The amino acids pool pattern of mutants and revertants is different from that in the wild type strain.