Consequences of a large-scale fragmentation experiment for Neotropical bats: disentangling the relative importance of local and landscape-scale effects

Context

Habitat loss, fragmentation and degradation are widespread drivers of biodiversity decline. Understanding how habitat quality interacts with landscape context, and how they jointly affect species in human-modified landscapes, is of great importance for informing conservation and management.

Objectives

We used a whole-ecosystem manipulation experiment in the Brazilian Amazon to investigate the relative roles of local and landscape attributes in affecting bat assemblages at an interior-edge-matrix disturbance gradient.

Methods

We surveyed bats in 39 sites, comprising continuous forest (CF), fragments, forest edges and intervening secondary regrowth. For each site, we assessed vegetation structure (local-scale variable) and, for five focal scales, quantified habitat amount and four landscape configuration metrics.

Results

Smaller fragments, edges and regrowth sites had fewer species and higher levels of dominance than CF. Regardless of the landscape scale analysed, species richness and evenness were mostly related to the amount of forest cover. Vegetation structure and configurational metrics were important predictors of abundance, whereby the magnitude and direction of response to configurational metrics were scale-dependent. Responses were ensemble-specific with local-scale vegetation structure being more important for frugivorous than for gleaning animalivorous bats.

Conclusions

Our study indicates that scale-sensitive measures of landscape structure are needed for a more comprehensive understanding of the effects of fragmentation on tropical biota. Although forest fragments and regrowth habitats can be of conservation significance for tropical bats our results further emphasize that primary forest is of irreplaceable value, underlining that their conservation can only be achieved by the preservation of large expanses of pristine habitat.

     

紫花苜蓿耗水规律及灌溉制度优化研究

为研究河套灌区紫花苜蓿的耗水规律,同时对现有灌溉制度进行优化,在田间试验的基础上,设置不同灌水水平对前两茬苜蓿进行了研究。结果表明:现蕾期和开花期是紫花苜蓿耗水的旺盛阶段,该阶段土壤水分亏缺会直接影响苜蓿产量的形成。通过多元线性回归的方法求解得到了两茬紫花苜蓿各生育期的敏感性系数,分别在0.103~0.731和0.041~0.375之间,且以现蕾期和开花期为最大,说明这两个生育阶段为苜蓿生长的关键阶段。以Jensen模型为基础,采用最小二乘法初步优化了两茬紫花苜蓿生育期内的灌溉制度,第1茬灌溉定额以1 400 m3/hm~2为宜,第2茬以2 300 m3/hm~2为宜,两茬灌水次数分别以4次和5次为最优。     

Prediction of parental combination for introduction of stay-green associated loci in wheat

In wheat, the increase of yield and stability associated traits can be achieved by combining parents containing the stay-green trait and favorable alleles for grain yield. The aim of this work was to analyze the genetic dissimilarity between wheat lines from stay-green and synchronized maturation groups and elite cultivars. Moreover, to propose promising combinations seeking the selection of high-grain yield and high bread-making quality genotypes containing stay-green trait. The experiment was conducted in a randomized block design with three replications in 2003, 2004, and 2005, using sister-lines with the presence and absence of stay-green trait and elite cultivars. Genetic variability exists among wheat strains from the synchronized stay-green maturation group and elite cultivars. Genotypes of maturation group stay-green obtained an average performance superior to the synchronized group. Crosses between stay-green lines and the CEP 29 and BRS 177 cultivars are promising in the selection of genotypes carrying the stay-green trait with high yield and bread-making quality.     

Does the application of silvicultural management models drive the growth and stem quality of sweet chestnut coppices towards sustainability?

New Forests - The coppice is a very flexible cultural system producing several calibers adapting to the demands of the market. Small-caliber roundwood from sweet chestnut (Castanea sativa Mill.)...     

Chitosan-Based Films with 2-Aminothiophene Derivative: Formulation,Characterization and Potential Antifungal Activity

In this study, films of chitosan and 2-amino-4,5,6,7-tetrahydrobenzo[b]thiophene-3-carbonitrile (6CN), a 2-aminothiophene derivative with great pharmacological potential, were prepared as a system for a topical formulation. 6CN-chitosan films were characterized by physicochemical analyses, such as Fourier-transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and scanning electronic microscopy (SEM). Additionally, the antifungal potential of the films was evaluated in vitro against three species of Candida (C. albicans, C. tropicalis, and C. parapsilosis). The results of the FTIR and thermal analysis showed the incorporation of 6CN in the polymer matrix. In the diffractogram, the 6CN-chitosan films exhibited diffraction halos that were characteristic of amorphous structures, while the micrographs showed that 6CN particles were dispersed in the chitosan matrix, exhibiting pores and cracks on the film surface. In addition, the results of antifungal investigation demonstrated that 6CN-chitosan films were effective against Candida species showing potential for application as a new antifungal drug.     

LED-Induced Chlorophyll Fluorescence Spectral Analysis for the Early Detection and Monitoring of Cadmium Toxicity in Maize Plants

Chlorophyll fluorescence spectral analysis permits detection, monitoring, and evaluation of abiotic stresses upon healthy plants using illumination of a light source in the UV?CVIS spectral range. This technique indirectly assesses the amount of physiological stress caused by photosynthetic damage, specifically damage to photosystem II, in plants. The objective of this study was to detect the toxicity of cadmium in maize plants via spectral analysis of chlorophyll fluorescence. The analysis is noninvasive and nondestructive and is used to follow the temporal evolution of changes in the chlorophyll content and physiological state of Zea mays L. seedlings under cadmium stress. Conventional techniques were also used to evaluate the dry matter production and Cd accumulation in plant leaves. Plants exhibited a notable reduction in dry matter production and chlorophyll levels with the administration of increasing doses of Cd in the nutrient solution. The fluorescence analysis was sensitive to changes caused by Cd in maize plants, detecting damage caused by different treatments before visual symptoms were observed. This technique has a practical application and produces rapid results that can be used in the evaluation of Cd-induced stress in plants and the detection of areas contaminated by this element.     

Total Phenolic Levels,In Vitro Antioxidant Properties,and Fatty Acid Profile of Two Microalgae,Tetraselmis marina Strain IMA043 and Naviculoid Diatom Strain IMA053, Isolated from the North Adriatic Sea

This work studied the potential biotechnological applications of a naviculoid diatom (IMA053) and a green microalga (Tetraselmis marina IMA043) isolated from the North Adriatic Sea. Water, methanol, and dichloromethane (DCM) extracts were prepared from microalgae biomass and evaluated for total phenolic content (TPC) and in vitro antioxidant properties. Biomass was profiled for fatty acid methyl esters (FAME) composition. The DCM extracts had the highest levels of total phenolics, with values of 40.58 and 86.14 mg GAE/g dry weight (DW in IMA053 and IMA043, respectively). The DCM extracts had a higher radical scavenging activity (RSA) than the water and methanol ones, especially those from IMA043, with RSAs of 99.65% toward 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)diammonium salt (ABTS) at 10 mg/mL, and of 103.43% against 2,2-diphenyl-1-picrylhydrazyl (DPPH) at 5 mg/mL. The DCM extract of IMA053 displayed relevant copper chelating properties (67.48% at 10 mg/mL), while the highest iron chelating activity was observed in the water extract of the same species (92.05% at 10 mg/mL). Both strains presented a high proportion of saturated (SFA) and monounsaturated (MUFA) fatty acids. The results suggested that these microalgae could be further explored as sources of natural antioxidants for the pharmaceutical and food industry and as feedstock for biofuel production.     

In Vitro Effect of the Reproductive Hormones on the Oxidative Burst Activity of Polymorphonuclear Leucocytes from Cows: A Flow Cytometric Study

In this study, the effect of reproductive hormones and substances with hormonal activity on the oxidative burst activity of blood polymorphonuclear leucocytes (PMN) high yielding dairy cows was evaluated. Different concentrations of: progesterone, oestradiol 17β, FSH, LH, GnRH, cortisol and PGF2α were incubated in vitro for 4 h with PMN of seven high milk yielding cows, during the period of anoestrous postpartum. Controls were run in parallel in which each hormone was replaced by its solvent. After incubation with hormones the competence of PMN to generate H₂O₂ was monitored by flow cytometry. A down‐regulation on the oxidative burst activity of PMA‐stimulated PMN was observed when cells were incubated with progesterone. Significant (p ≤ 0.001) differences between control and progesterone incubated cells were observed from 6.56 μg/ml. The same predisposition was observed when PMNs were incubated with cortisol. Besides for all concentrations employed, a decrease in the burst activity was observed, only beyond 0.19 mg/ml, statistical differences between the results obtained by the control and the cortisol incubated cells were obtained. Concerning oestradiol 17β, an increase on H₂O₂‐production was observed when PMN were incubated with 15 pg/ml and 45 pg/ml of this steroid (p ≤ 0.05), followed by a depression of the cell’s activity when unphysiological concentrations were employed. Significant (p ≤ 0.05) differences between the obtained with the control and oestradiol 17β incubated cells were observed only in the highest concentration of oestradiol. No statistical differences were observed in the metabolic burst activity of PMN incubated with FSH, GnRH and LH when compared with the results obtained by the control.     

Intra-articular pressure profiles of the cadaveric equine fetlock joint in motion

The study of the influence of motion and initial intra-articular pressure (IAP) on intra-articular pressure profiles in equine cadaver metatarsophalangeal (MTP) joints was undertaken as a prelude to in vivo studies. Eleven equine cadaver MTP joints were submitted to 2 motion frequencies of 5 and 10 cycles/min of flexion and extension, simulating the condition of lower and higher (double) rates of passive motion. These frequencies were applied and pressure profiles generated with initial normal intra-articular pressure (-5 mmHg) and subsequently 30 mmHg intra-articular pressure obtained by injection of previously harvested synovial fluid. The 4 trials performed were 1) normal IAP; 5 cyles/min; 2) normal IAP; 10 cycles/min; 3) IAP at 30 mmHg; 5 cycles/min and 4) IAP at 30 mmHg; 10 cycles/min. The range of joint motion applied (mean +/- s.e.) was 67.6+/-1.61 degrees with an excursion from 12.2+/-1.2 degrees in extension to 56.2+/-2.6 degrees in flexion. Mean pressure recorded in mmHg for the first and last min of each trial, respectively, were 1) -5.7+/-0.9 and -6.3+/-1.1; 2) -5.3+/-1.1 and -6.2+/-1.1; 3) 58.8+/-8.0 and 42.3+/-7.2; 4) 56.6+/-3.7 and 40.3+/-4.6. Statistical analyses showed a trend for difference between the values for the first and last minute in trial 3 (0.05>P<0.1) with P = 0.1 and significant difference (P = 0.02) between the mean IAP of the first and last min in trial 4. The loss of intra-articular pressure associated with time and motion was 10.5, 16.9, 28.1 and 28.9% for trials 1-4, respectively. As initial intraarticular pressure and motion increased, the percent loss of intra-articular pressure increased. The angle of lowest pressure was 12.2+/-1.2 degrees (mean +/- s.e.) in extension in trials 1 and 2. In trials 3 and 4, the lowest pressures were obtained in flexion with the joints at 18.5+/-2.0 degrees (mean +/- s.e.). This demonstrated that the joint angle of least pressure changed as the initial intra-articular pressure changed and there would not be a single angle of least pressure for a given joint. The volume of synovial fluid recovered from the MTP joints in trial 3 compared to 4 (trials in which fluid was injected to attain IAP of 30 mmHg) was not significantly different, supporting a soft tissue compliance change as a cause for the significant loss of intra-articular pressure during the 15 min of trial 4. The pressure profiles generated correlate well with in vivo values and demonstrated consistent pressure profiles. Our conclusions are summarised as follows: 1. Clinically normal equine MTP joints which were frozen and then later thawed were found to have mostly negative baseline intra-articular pressures, as would be expected in living subjects. 2. Alternate pressure profiles of the dorsal and plantar pouch at baseline intra-articular pressure document the presence of pressure forces that would support 'back and forth' fluid movement between joint compartments. This should result in movement of joint fluid during motion, assisting in lubrication and nutrition of articular cartilage. 3. If joint pressure was initially greater than normal (30 mmHg), as occurs in diseased equine MTP joints, joint motion further increased joint capsule relaxation (compliance) and, therefore, reduced intra-articular pressure. 4. Peak intra-articular pressures reached extremely high values (often >100 mmHg) in flexion when initial pressure was 30 mmHg. Joint effusion pressures recorded for clinical MCP joints are frequently 30 mmHg. These IAP values are expected to produce intermittent synovial ischaemia in clinical cases during joint flexion. 5. Additional in vivo studies are necessary to confirm our conclusions from this study and to identify the contributions of fluid absorption and the presence of ischaemia in a vascularised joint.     

Relation between Physical Properties of the Zona Pellucida and Viability of Bovine Embryos after Slow-freezing and Vitrification

In vitro-produced bovine morulae/blastocyst embryos (n = 119) were slow-frozen and vitrified and the physical alterations of the zona pellucida (ZP) was observed by scanning electron microscopy (SEM) to find an explanation for the loss of developmental capacity of the embryos after freezing/thawing. A control group was provided, in which embryos (n = 38) were neither frozen nor vitrified. Embryos were in vitro-cultured in a standard CO2 Heraeus incubator and their viability was assessed 24 and 48 h after the start of culture, evaluating their morphological aspect. After 24 h of culture, embryo survival rate for slow-freezing/thawed (n = 23), vitrified/thawed (n = 20) and control embryos (n = 20) was 39, 27 and 90%, and 35, 14 and 65% after 48 h of culture, respectively. For evaluation of physical changes occurring in ZP, 20 embryos were slow-frozen, 18 were vitrified and 18 were used as control. All embryos were fixed, dried and examined under an SEM. Embryo's diameter, as well as the number of pores and their diameter was measured in squares of 6.4 microm width. We observed that, on average, the diameter of the embryos (92.26 +/- 10.15 microm) did not differ significantly among all embryos. As far as the diameter of the pores in the outer surface of the ZP is concerned, the results revealed a significant difference (P < 0.05) between control (0.48 +/- 0.0025 microm), slow-frozen (0.34 +/- 0.0007 microm) and vitrified (0.27 +/- 0.0006 microm) embryos. For the number of pores, statistical differences (p < 0.05) were observed between control and vitrified embryos (45.4 +/- 7.3 vs 38.2 +/- 8.2). It is possible that ZP functions as a barrier which is positive when dealing with pathogens, but is harmful when nutrients were supplied from the outside, especially at 48 h of culture. Results indicate that the steps of cryopreservation cause alterations in ZP, with irreversible damage on the further developmental competence of bovine embryos.