Nuclear conditions in haploid Pelargonium in vivo and in vitro

In the shoot apices of the haploid Pelargonium cultivar Kleine Liebling, all mitoses are haploid (n = 9); however, ca. 20% of the interphase nuclei have DNA contents greater than 2C (up to 4C), indicating a tendency to chromosome endoreduplication in this material. — In internodes in vivo, the few mitoses present are haploid (quite probably, cambium cells); in addition to haploid interphases (1C to 2C DNA contents), endoreduplicated (endopolyploid) nuclei and nuclei in the course of endoreduplication occur with a frequency of ca. 40–50% (DNA contents up to 8C). — When internodes are cultured in vitro, differentiated cells are stimulated to divide, thus forming a population of diploid and tetraploid mitoses in addition to the preexistent meristem (haploid) cell population. In the process of time, diploid and tetraploid mitoses continue to be present in the callus, whilst haploid mitoses may decrease in number and eventually disappear. All mitoses analyzed had euploid chromosome numbers (9, 18 and 36) and their DNA contents were correspondingly 2C, 4C and 8C. Since no extensive chromosome counts were made, aneuploidy in the cultured material cannot be excluded; but, if occurring, it should be rather rare. — Under the experimental conditions used, prolonged culture in vitro leads to the production of nuclei with DNA contents (16C and 32C) greater than those occurring in vivo (8C), due to one and two additional DNA replications respectively beyond the limits attained in vivo. Even in these cultures, however, a population of the meristematic haploid cell line (DNA values 1C to 2C) is still present. — The present results are discussed in their relations with previous works on nuclear conditions in vivo and in vitro and on regeneration processes in cultured tissues in plants.     

A rapid shift to high-grain diet results in dynamic changes in rumen epimural microbiome in sheep

The rapid shift to high-grain (HG) diets in ruminants can affect the function of the rumen epithelium, but the dynamic changes in the composition of the epithelium-associated (epimural) bacterial community in sheep still needs further investigation. Twenty male lambs were randomly allocated to four groups (n = 5). Animals of the first group received hay diet and represented a control group (CON). Simultaneously, animals in the other three groups (HG groups) were rapidly shifted to an HG diet (60% concentrate)which continued for 7 (HG7), 14 (HG14) and 28 (HG28) days, correspondingly. Results showed that ruminal pH dramatically decreased due to the rapid shift to the HG diet (P <0.001), while, the concentrations of butyrate (P <0.001), lactate (P = 0.001), valerate (P = 0.008) and total volatile fatty acids (P = 0.001) increased. Diversity estimators showed a dramatic decrease after the shift without recovering as the HG feeding continued. The principal coordinates analysis showed that CON group clustered separately from all HG groups with the presence of significant difference only between HG7 and HG28 (P = 0.034). The non-parametric multivariate analysis (npmv R-package) deduced that the primary significant differences in phyla and phylogenetic investigation of communities by reconstruction of unobserved states (PICRUSt)-predicted Kyoto Encyclopedia of Genes and Genomes (KEGGs) was attributed mainly to the diet composition (P <0.001, P = 0.001) compared to its application period (P = 0.140, 0.545) which showed a significant effect only on the genus (P = 0.001) and the operational taxonomic units (OTUs) level (P = 0.011). The Kruskal–Wallis test deduced that six phyla showed a significant effect due to the shift in diet composition. At the genus level, HG feeding altered the abundance of 12 taxa, four of which showed a significant variation due to the duration of the HG diet application. Similarly, we found that 21 OTUs showed significant variations due to the duration of the HG diet application. Furthermore, the genes abundance predicted by PICRUSt revealed that the HG feeding significantly affected seven metabolic pathways identified in the KEGG. Particularly, the abundance of gene families associated with carbohydrates metabolism were significantly higher in HG feeding groups (P = 0.027). Collectively, these results revealed that the rapid transition to an HG diet causes dramatic alterations in ruminal fermentation and the composition and function of ruminal epithelium-associated microbiome in sheep, while, the duration of the HG diet application causes drastic alterations to the abundance of some species.     

Self-Organizing Maps in Revealing Variation in Non-obligatory Riverine Fish in Long-term Data

Sensitiveness to the overall influence of the river channel regulation, impoundment and pollution was studied for 12 non-obligatory riverine (NOR) fish species in the Warta River, Poland, over the period of 1963–1998. Their total abundance has not considerably changed unlike the structure of their aggregation, which was revealed by a self-organizing map (SOM, Kohonen unsupervised artificial neural network) almost perfectly separating 1960s samples from 1990s ones. The greatest changes in proportion were recorded for the dominant roach Rutilus rutilus (from 28.6 to 60.0%), perch Perca fluviatilis (1.9 to 9.5%), pike Esox lucius (2.9 to 4.9%), and the former codominant bleak Alburbus alburnus (22.9 to 1.8%). They resulted from highly significant (p < 0.001), reaching even one order of magnitude, differences in the abundance of these species. Such remarkable alternations in dominant NOR ichthyofauna obviously influenced the whole fish assemblage structure, which was best illustrated by a clear vertical gradient over SOM in Simpson and Shannon indices. Thus, NOR species, both studied together and separately, can supply valuable information on the fish assemblage dynamics and should not be neglected in temporal analyses, often focused only on vulnerable obligatory riverine, migratory and/or endemic species.     

Spectrum of in vivo and in vitro cell-mediated immune responses in coccidioidomycosis.

The cell-mediated immune responses of 12 healthy, coccidioidin skin-test positive subjects (Group I) were compared with those of 15 healthy, coccidioidin skin-test positive persons who had primary asymptomatic coccidiodomycosis, (Group II), 12 patients with active, pulmonary coccidioidomycosis (Group III), four patients with disseminated disease (Group IV), and five patients who had been in clinical remission for 1 year or longer (Group V). Lymphocytes from healthy subjects in Groups I and II responded in vitro to Coccidioides immitis antigen by undergoing an increased DNA synthesis (lymphocyte transformation) and/or by producing macrophage migration inhibitory factor (MIF). In contrast, patients in Groups III and IV failed to respond to Coccidioides antigens in vivo (skin tests) or in vitro (lymphocyte transformation and production of MIF). The responses of subjects in Group V with inactive disease fell in between those of healthy donors in Groups I and II and patients in Groups III and IV. The cellular immune defect, in terms of antigen recognition, appeared to be specific for C. immitis in all but one patient.     

Immunosuppression in experimental cryptococcosis in rats

Using a rat model, we have previously demonstrated that infection with Cryptococcus neoformans can trigger the production of a series of suppressor cells that specifically inhibit the cell-mediated immune response to a non-related antigen, human serum albumin (HSA), that has been injected 7 days after the infection. We previously determined that the cryptococcal infection induces afferent suppressor or suppressor induction cells (Ts₁) to HSA. The primary objective of the present study was to investigate the suppressor cells involved in the efferent phase of delayed-type hypersensitivity (DTH) response to HSA in rats infected with C. neoformans and immunized with the non-related antigen and determine the role that the Ts₁ cell plays in the induction of that cell. For this purpose, the spleen mononuclear (SpM) cells containing the Ts₁ or SpM cells from immunized non-infected rats (used as donor controls) were transferred to two groups of syngeneic naive recipients (first recipients). Later, the SpM cells from both groups of animals were transferred to rats immunized with HSA (second recipients). The efferent limb of the DTH response to HSA was suppressed in the recipients that received SpM cells from donors injected with Ts₁ cells. Additional HSA antigen was not required for induction of these efferent suppressor cells. Furthermore, we here show that these cells are resistant to treatment with cyclophosphamide (Cy), and that they can activate another suppressor population. The latter are Cy sensitive and are present in the immune recipient.     

Iron-induced oxidative DNA damage in rat sperm cells in vivo and in vitro

We investigated whether acute iron intoxication causes oxidative DNA damage, measured in terms of 7-hydro-8-oxo-2′-deoxyguanosine, 8-oxodG, in nuclear DNA in testes and epididymal sperm cells in vivo and in vitro in rats. In addition, we investigated levels of the modified nucleoside in liver and kidney and measured its urinary excretion.

Sperm cells were isolated from the epididymides and the testes cells were isolated after homogenisation. In vitro, the sperm and testes cells were incubated with increasing concentrations of FeCl₂ ranging from 0 to 600 μM. The median (range) levels of 8-oxodG/10⁵ dG in the epididymal sperm cells increased from 0.48 (0.42–0.90) to 15.1 (11.4–17.6) (p < 0.05), whereas the level rose from 0.63 (0.22–0.81) to 8.8 (4.5–11.6) (p < 0.05) at 0 and 600 μM, respectively, in the testicular cells.

In vivo groups of 7–8 rats received 0, 200 or 400 mg iron/kg as dextran i.p. After 24h, epididymal sperm cells, testes, kidneys and liver were collected for analysis. Kidney and sperm DNA showed a significant increase in 8-oxodG in the iron-treated animals. The median (range) values of the 8-oxodG/10⁵ dG in the epididymal sperm cells rose from 0.66 (0.38–1.09) to 1.12 (0.84–5.88) (p < 0.05) at 0 and 400 mg iron/kg, respectively, whereas the values in the testes and liver showed no significant change. In the kidneys the 8-oxodG/10⁵ dG median (range) values were 0.98 (0.73–1.24), 1.21 (1.13–1.69) and 1.34 (1.12–1.66) after 0, 200 and 400 mg iron/kg, respectively (p < 0.05).

The 8-oxodG-excretion rate was measured in 24 h urine before and after iron treatment. The rate of urinary 8-oxodG excretion increased from 129 (104–179) pmol/24 h before treatment to 147 (110–239) pmol/24h after treatment in the group receiving 400 mg iron/kg (p < 0.05).

The results indicate that acute iron intoxication may increase oxidative damage to sperm and kidney DNA.     

Galactolipid synthesis in chromoplasts in vitro

Isolated chromoplasts from Narcissus pseudonarcissus flowers contain: a fatty acid synthesizing system; acyl-CoA synthetase (EC 6.2.1.3); glycero-phosphate acyltransferase (EC 2.3.1.15); acylglycero-phosphate acyltransferase; phosphatidate phosphatase (EC 3.1.3.4); diacylglycerol galactosyltransferase (EC 2.4.1.46); and diacylgalactosylglycerol galactosyltransferase, i.e. all enzymatic activities necessary for the synthesis of diacylgalactosylglycerol and diacylgalabiosylglycerol from acetate, HCO _- ³ , sn-glycerol 3-phosphate, and UDP-d-galactose. Diacylgalactosylglycerol and diacylgalabiosylglycerol, however, are synthesized from these precursors to only a very low extent in an in vitro system. This is attributed to a specificity of diacylglycerol galactosyltransferase for highly unsaturated diacylglycerols. Specificities of acyltransferase reactions were also found.     

Mitochondrial distribution and meiotic progression in canine oocytes during in vivo and in vitro maturation

The objective was to evaluate mitochondrial distribution, and its relationship to meiotic development, in canine oocytes during in vitro maturation (IVM) at 48, 72, and 96 h, compared to those that were non-matured or in vivo matured (ovulated). The distribution of active mitochondria during canine oocyte maturation (both in vitro and in vivo) was assessed with fluorescence and confocal microscopy using MitoTracker Red (MT-Red), whereas chromatin configuration was concurrently evaluated with fluorescence microscopy and DAPI staining. During IVM, oocytes exhibited changes in mitochondrial organization, ranging from a fine uniform distribution (pattern A), to increasing clustering spread throughout the cytoplasm (pattern B), and to a more perinuclear and cortical distribution (pattern C). Pattern A was mainly observed in germinal vesicle (GV) oocytes (96.4%), primarily in the non-matured group (P < 0.05). Pattern B was seen in all ovulated oocytes which were fully in second metaphase (MII), whereas in IVM oocytes, ∼64% were pattern B, irrespective of duration of culture or stage of nuclear development (P > 0.05). Pattern C was detected in a minor percentage (P < 0.05) of oocytes (mainly those in first metaphase, MI) cultured for 72 or 96 h. In vitro matured oocytes had a minor percentage of pattern B (P < 0.05) and smaller mitochondrial clusters in IVM oocytes than ovulated oocytes, reaching only 4, 11, and 17% of MII at 48, 72, and 96 h, respectively. Thus, although IVM canine oocytes rearranged mitochondria, which could be related to nuclear maturation, they did not consistently proceed to MII, perhaps due to incomplete IVM, confirming that oocytes matured in vitro were less likely to be competent than those matured in vivo.     

Homology in capsular transformation reactions in Pneumococcus

Summary Experiments were carried out to determine the relative effect of homology inside or outside of the capsular genomes of donor and recipient strains of pneumococci on the frequency of transfer of capsular markers. In one series of experiments, 3 recipient strains were transformed to CapIII⁺ by DNA from 2 donor strains. Recipient strains (III)capIII D6 ¹, (II)capIII D15 P1 ¹, and (II)capII-1 ¹ were each transformed to CapIII⁺ at different absolute frequencies dependent upon the amount of genetic information that the strain had to acquire. The chromosomal background of the donor strain carrying the CapIII capsular genome had no influence on the results, however, for each strain was transformed at the same frequency by DNA from donor strain (II)CapIII⁺ or donor strain (III)CapIII⁺. In a second series of experiments, 2 (I)CapIII-strains, a (II)CapIII-strain and a (III)CapIII-strain were transformed to heterologous type I and binary type I-III with DNA from donor strains (I)CapI⁺, (II)CapI⁺, and (III)CapI⁺. Again, the chromosomal background of the donor strain was unimportant to the results. The origin of the recipient strain, however, markedly influenced the frequency of transformation. (I)CapIII-strains were transformed to CapI⁺ at about 10 times the frequency and to CapI-III at from 18–6000 times the frequency of the other CapIII-strains. Consideration of the results leads to the conclusion that transformation of CapIII-strains to CapI⁺ and transformation of CapI-strains to CapIII⁺ are not reciprocal reactions; CapI-strains lose less information in transformation to CapIII⁺ than CapIII-strains gain in transformation to CapI⁺. In (I)CapIII-recipient strains, the residual information from the CapI capsular genome is responsible for the higher frequency of transformation to both CapI⁺ and to CapI-III. It is suggested that addition of exogenous linear DNA to a recipient chromosome to give rise to binary strains occurs when sequence homology with the recipient is limited to one end of a piece of transforming DNA. Models to explain the results (Figs. 1 through 3) are consistent with the experimental findings and are amenable to further testing.     

Gender-related differences in maximum mechanical power output in short-term activities in children and adolescents

The study was designed to examine the gender-related differences in maximum mechanical power output in various short-burst activities during growth. The subject sample consisted of four subgroups: 9 boys (14.11 +/- 0.6 yr), 9 boys (10.67 +/- 0.71 yr), 7 girls (14.29 +/- 0.49 yr), 7 girls (10.57 +/- 0.54 yr). We measured peak power (PP), mean power (MP), fatigue index (FI) during 30-s WAnT, squat jump height (SJH) and power (SJP), and counter movement jump height (CMJH) and power (CMJP), maximum speed over 20-metre distance (S20). Lactation concentration was measured in the 3rd and 5th minutes after the WAnT Ratio normalisation and ANCOVA were used to remove the influence of the differences in muscle (MM) and body mass (BM). Male adolescents had higher absolute values of PP (P < 0.05), MP (P < 0.05) than female. Ratio normalisation showed that boys had higher PP/BM (P < 0.05), PP/MM (P < 0.05), MP/BM (P < 0.05), MP/MM (P < 0.06) than girls. The ANCOVA adjustment for MM showed differences between genders in PP (P < 0.001), MP (P < 0.001), SJH (P < 0.05), SJP (P < 0.05) and CMJP (P < 0.001), whereas the ANCOVA adjustment for BM showed differences only in PP (P < 0.001), MP (P < 0.001). Prepubertal boys had higher absolute values only in SJP (P < 0.05). We concluded that variations in body composition could not be the only key to gender-related differences in power output in short-burst activities.     

Transition of cancer in populations in India

Background & objectivesAn assessment of transition of cancer in India during the past 30 years, according to changes in demographic and epidemiologic risk factors was undertaken.Materials & methodsCancer registry data (http://www.ncdirindia.org), (population coverage <10%), was compared with transition in life-expectancy and prevalence on smoking, alcohol and obesity. We fitted linear regression to the natural logarithm of the estimated incidence rates of various cancer registries in India.ResultsBurden of cancer in India increased from 0.6 million in 1991 to 1.4 million in 2015. Among males, common cancers are lung (12.0%), mouth (11.4%), prostate (7.0%), and tongue (7.0%) and among females, they are breast (21.0%), cervix-uteri (12.1%), ovary (6.9%), and lung (4.9%) in 2012. Increased life-expectancy and population growth as well as increased use of alcohol and increased prevalence of overweight/obesity reflected an increase in all cancers in both genders except a reduction in infection-related cancers such as cervix-uteri and tobacco-related cancers such as pharynx (excludes nasopharynx) and oesophagus.Interpretation & conclusionTransition in demographics and epidemiologic risk factors, reflected an increase in all cancers in both genders except a reduction in a few cancers. The increasing incidence of cancer and its associated factors demands a planned approach to reduce its burden. The burden assessment needs to be strengthened by increasing the population coverage of cancer registries. Continued effort for tobacco prevention and public health efforts for reducing obesity and alcohol consumption are needed to reduce the cancer burden.     

Differences in motivations and weight loss behaviors in young adults and older adults in the national weight control registry

Objective:

The goal of this study was to compare young adults (YA) and older adults (OA) in the National Weight Control Registry on motivations for weight loss and weight‐loss behaviors.

Design and Methods:

Participants (n = 2,964, 82% female, 94% White, BMI = 24.8 ± 4.4) were divided into two age groups (18‐35 vs. 36‐50) and compared on motivations, strategies for weight loss, diet, physical activity (PA), and the three‐factor eating questionnaire.

Results:

YA were 28.6% of the sample (n = 848). YA and OA achieved similar weight losses (P = 0.38), but duration of maintenance was less in YA (43 vs. 58 months, P < 0.001). YA were more likely to cite appearance and social motivations for weight loss, were less motivated by health, and were less likely to report a medical trigger for weight loss (P's < 0.001). YA were more likely to use exercise classes and to lose weight on their own, and less likely to use a commercial program (P's < 0.001). YA reported engaging in more high‐intensity PA (P = 0.001). There were no group differences in total calories consumed (P = 0.47), or percent calories from fat (P = 0.97), alcohol (P = 0.52), or sugar‐sweetened beverages (P = 0.26).

Conclusions:

YA successful weight losers (SWL) are motivated more by appearance and social influences than OA, and physical activity appears to play an important role in their weight‐loss efforts. The differences reported by YA and OA SWL should be considered when developing weight‐loss programs for YA.     

Low Cadmium Levels in Urine of Residents in two Prefectures where Cadmium Levels in Locally Harvested Brown Rice are Higher than in other Prefectures in Japan

Recent publications in Japan suggest that Cd in river beds and locally harvested rice tend to be higher in seven prefectures in the north-eastern part on the coast of the Sea of Japan (the high-Cd zone). The present study was initiated to investigate the current level of exposure to Cd and possible health effects among local populations in the zone. Thus, levels of Cd and three tubular dysfunction markers [i.e., α ₁-MG, β ₂-MG, and N-acetyl-β-d-glucosaminidase (NAG)] were examined in urine of local residents (700 and 704 adult women, respectively) in two prefectures (prefecture 1 and prefecture 7), which were located in the north-east (prefecture 1) and south-west ends (prefecture 7) of the high-Cd zone. Urinary Cd levels [e.g., 0.99 and 0.78 μg/l as geometric mean (GM) for observed (non-corrected) values, respectively] in prefecture 1 and prefecture 7 were comparable to the levels in other parts of Japan (All Japan-A; 0.99 μg/l). Correspondingly, GM values for α ₁-MG (2.29 and 1.99 mg/l vs. 2.17 mg/l for All Japan-A) and for β ₂-MG (87 and 80 μg/l vs. 99 μg/l for All Japan-A) were not elevated, and NAG also stayed unchanged (2.89 and 2.87 units/l for prefecture 1 and prefecture 7, respectively). Evaluation in combination with the findings in other five prefectures in the zone suggests that Cd exposure is equal to the national average both in prefecture 1 and in prefecture 7, whereas Cd exposure appeared to be elevated in the central part of the zone. The observation appears to be on line with geographical location of the two prefectures that they are on the two ends of the zone of high natural Cd background.     

Interannual variations in GPP in forest ecosystems in Southwest China and regional differences in the climatic contributions

Forest ecosystem plays an important role as carbon sinks in Southwest China. Currently, remote sensing technology has been widely used to substantially model the high temporal and spatial variation in gross primary production (GPP) at a site or regional scale. However, during the growing season, the regional uncertainty of GPP in the forest ecosystem and the relative contributions of climate variations to interannual variation (IAV) of GPP are not well understood across Southwest China. Our research focuses on the joint analysis of the three-cornered hat (TCH) algorithm and uses the contribution index to analyse the model's uncertainties varying with plant functional types (PFTs), climate zones, and the contribution of climate variabilities to GPP IAV. Here, three GPP datasets are used to investigate how climate variabilities contribute to the GPP IAV during the growing season. The uncertainties in GPP vary from 829.33 g C m⁻² year⁻¹ to 2031.86 g C m⁻² year⁻¹ for different models in different climate zones and different PFTs. Additionally, the results highlight that precipitation dominates the interannual variation in GPP in forest ecosystem during the growing season in Southwest China. It makes the largest contribution (34.46%) to the IAV of GPP in the climate zone of E (cold subtropical highland area) and the largest contribution (80.83%) to PFTs of the MF (mixed forest). Our study suggests the availability and applicability of GPP products can be used to assess GPP uncertainties and analyse the contributions of climate factors to GPP IAV in forest ecosystem or other ecosystems.     

Corpuscular oxidative stress in desert sheep naturally deficient in copper

Oxidative stress arises when there is an imbalance between radical-generating and radical-scavenging activity; it may therefore cause an increase in oxidation products and cell damage. This study aimed to determine antioxidant status, lipid peroxidation, and their relation to anemia of grazing sheep deficient in copper (Cu). For this purpose, 39 male lambs of native (Balady) breed, aged 6–7 months and reared in El-Dakhla oasis (in the western Egyptian desert), were divided according to plasma Cu (pCu) concentration into three groups, marginally deficient (MD, pCu = 4–8 μmol/l, n = 12), functionally deficient (FD, pCu < 3 μmol/l, n = 12) and control (pCu > 9 μmol/l, n = 15). Jugular blood was sampled for determination of red blood cell count (RBC), packed cell volume (PCV), hemoglobin concentration (Hb), plasma ceruloplasmin activity (pCp), antioxidant activities of erythrocytic superoxide dismutase (eSOD), catalase (eCAT), glutathione peroxidase (eGSH-Px), and levels of erythrocytic malondialdehyde (eMDA, as a biomarker of lipid peroxidation). The Cu-deficient lambs were characterized by microcytic hypochronic anemia accompanied by decreased pCp, eSOD, eCAT and eGSH-Px activities and increased eMDA level when compared to the controls. The indices of anemia, pCp and eSOD were lower and eMDA was higher in FD compared to MD lambs. The enhanced eMDA was strongly correlated (P < 0.01) with the inhibited activity of pCu (r = −0.79), pCp (r = −0.65) and eSOD (r = −0.71) and to a lesser extent (P < 0.05) with eGSH-Px (r = −0.38) and eCAT (r = −0.41). In addition, eMDA was negatively correlated (P < 0.01) with RBC (r = −0.75), PCV (r = −0.69) and Hb (r = −0.72). This study suggests that Cu-deficient lambs incur an erythrocytic oxidative damage secondary to impaired oxidant defenses, which may be one of the mechanisms underlying Cu deficiency-induced anemia in grazing sheep.     

Soil respiration in six temperate forests in China

Scaling soil respiration (R_S), the major CO₂ source to the atmosphere from terrestrial ecosystems, from chamber‐based measurements to ecosystems requires studies on variations and correlations of R_S from various biomes and across geographic regions. However, few studies on R_S are available for Chinese temperate forest despite the importance of this forest in the national and global carbon budgets. In this study, we conducted 18‐month R_S measurements during 2004–2005 in six temperate forest types, representing the typical secondary forest ecosystems across various site conditions in northeastern China: Mongolian oak (Quercus mongolica Fisch.), aspen‐birch (Populous davidiana Dode and Betula platyphylla Suk.), mixed deciduous (no dominant tree species), hardwood (dominated by Fraxinus mandshurica Rupr., Juglans mandshurica Maxim., and Phellodendron amurense Rupr.) forests, Korean pine (Pinus koraiensis Sieb. et Zucc.) and Dahurian larch (Larix gmelinii Rupr.) plantations. Our specific objectives were to: (1) explore relationships of R_S against soil temperature and water content for the six forest ecosystems, (2) quantify annual soil surface CO₂ flux and its relations to belowground carbon storage, (3) examine seasonal variations in R_S and related environmental factors, and (4) quantify among‐ and within‐ecosystem variations in R_S. The R_S was positively correlated to soil temperature in all forest types, and was significantly influenced by the interactions of soil temperature and water content in the pine, larch, and mixed deciduous forests. The sensitivity of R_S to soil temperature at 10 cm depth (Q₁₀) ranged from 2.61 in the oak forest to 3.75 in the aspen‐birch forests. The Q₁₀ tended to increase with soil water content until reaching a threshold, and then decline. The annual R_S for the larch, pine, hardwood, oak, mixed deciduous, and aspen‐birch forests averaged 403, 514, 781, 785, 786, and 813 g C m^?2 yr^?1, respectively. The annual R_S of the broadleaved forests was 72% greater than that of the coniferous forests. The annual R_S was positively correlated to soil organic carbon (SOC) concentration at O horizon (R²=0.868) and total biomass of roots <0.5 cm in diameter (R²=0.748). The coefficient of variation (CV) of R_S among forest types averaged 25% across the 18‐month measurements. The CV of R_S within plots varied from 20% to 27%, significantly (P<0.001) greater than those among plots (9–15%), indicating the importance of the fine‐scaled heterogeneity in R_S. This study emphasized that variations in soil respiration and potential sampling bias should be appropriately tackled for accurate soil CO₂ flux estimates.     

Analysis of sterols in selected bloom-forming algae in China

Sterols, a group of stable lipid compounds, are often used as biomarkers in marine biogeochemical studies to indicate sources of organic matter. In this study, sterols in 13 species of major bloom-forming algae in China, which belong to Dinophyceae, Bacillariophyceae, Ulvophyceae, and Pelagophyceae, were analyzed with gas chromatography-mass spectrometry (GC–MS) to test their feasibility in representing different types of harmful algal blooms (HABs). It was found that (24Z)-stigmasta-5,24-dien-3β-ol (28-isofucosterol) was a major sterol component in green-tide forming macroalga Ulva prolifera. In bloom-forming dinoflagellates Alexandrium spp., Prorocentrum micans and Scrippsiella trochoidea, (22E)-4α,23-dimethyl-5α-ergost-22-en-3β-ol (dinosterol) was detected in addition to cholest-5-en-3β-ol (cholesterol), (22E)-ergosta-5,22-dien-3β-ol, (22E)-stigmasta-5,22-dien-3β-ol and other minor sterol components. In brown-tide forming pelagophyte Aureococcus anophagefferens, (24E)-24-propylcholesta-5,24-dien-3β-ol ((24E)-24-propylidenecholesterol) and (24Z)-24-propylcholesta-5,24-dien-3β-ol ((24Z)-24-propylidenecholesterol) were detected together with cholesterol, (22E)-stigmasta-5,22-dien-3β-ol, stigmast-5-en-3β-ol and campest-5-en-3β-ol. Among the selected bloom-forming diatoms, Chaetoceros sp. and Pseudo-nitzschia spp. only produced cholesterol, while Cylindrotheca closterium produced solely (22E)-ergosta-5,22-dien-3β-ol. Sterol content in four bloom-forming algal species correlates well with their biomass or abundance. It's proposed that 28-isofucosterol could serve as a promising biomarker for green algae in green-tide studies. Dinosterol and (24Z)-24-propylidenecholesterol can be used as potential biomarkers to represent bloom-forming dinoflagellates and pelagophytes, while (22E)-ergosta-5,22-dien-3β-ol is not a good indicator for diatoms.     

Plasma glucose response and glycemic indices in pigs fed diets differing in in vitro hydrolysis indices

Different dietary starch sources can have a great impact in determining starch digestion potential, thus influencing the postprandial blood glucose response. Our objectives were to define: (i) the incremental plasma glucose response in pigs fed diets containing various sources of starch differing in in vitro digestion patterns, (ii) the in vivo glycemic index (GI) values for the same diets, (iii) the possible relationship between in vitro and in vivo data. Diets, formulated with 70% of starch from five heterogeneous sources, were characterized in depth by using two distinct in vitro evaluations. The first one was based on the Englyst-assay for nutritional classification of starch fractions, whereas the second one was based on a time-course multi-enzymatic assay up to 180 min from which the hydrolysis indices (HIs) were calculated and used as a link between the physicochemical properties of starch from diets and the in vivo responses. For the in vivo study, five jugular-catheterized pigs (35.3 ± 1.1 kg body weight) were fed one of the five diets for 6-day periods in a 5 × 5 Latin square design. On day 5, blood was collected for 8 h postprandially for evaluating glucose appearance. On day 6, blood was collected for 3 h postprandially for the estimation of the GI. Starchy diets differed for rapidly digestible starch (from 8.6% to 79.8% of total starch (TS)) and resistant starch contents (from 72.5% to 4.5% of TS). Wide between-diets variations were recorded for all the kinetic parameters and for the HI calculated from the in vitro digestion curves (P < 0.05). On the basis of the obtained HI, diets contained starch with a very low to a very high in vitro digestion potential (ranging from 26.7% to 100.0%; P < 0.05). The glucose response differed among diets (P < 0.05), with marked differences between 15 and 120 min postprandial. Overall, the ranking of incremental glucose appearance among diets agreed with their in vitro HI classification: high HI diets increased plasma glucose response more (P < 0.05) than low HI diets. Lastly, different in vivo GIs were measured (ranging from 30.9% to 100.0%; P < 0.05). The relationship between HI and GI showed a high coefficient of determination (R² = 0.95; root mean square error (RMSE) = 15.8; P < 0.05). In conclusion, diets formulated with starches with a wide range in HI potential can strongly affect the postprandial glucose response in pigs.