High-resolution ultrasonography of xenografted domestic cat ovarian cortex

Transplantation of ovarian tissue has high potential for female gamete conservation. However, optimal timing of oocyte recovery for in vitro maturation and fertilization is still critical. Therefore the aim of the present study was to use high-resolution transcutaneous ultrasonography to monitor follicular development within xenografted ovarian tissue. Ovarian cortex fragments (n=44) from domestic cats were transplanted into athymic nude rats (n=12). Graft development in the animals was assessed weekly by high frequency ultrasound (10-22 MHz) under two different FSH regimes. Blood collection for serum estradiol determination and vaginal smears were performed simultaneously. The xenografts were removed at different time points according to the ultrasound findings. The survival rate of the transplants 4 weeks after surgery was 54.5% and antral follicular growth was observed within 10 grafts from 5 different hosts (8.6 +/- 6.43 follicles per graft). Early follicle antrums could be detected from 0.4 mm onwards. The growth rate of the antral cavity was calculated from weekly measurements (0.56 +/- 0.44 mm per week). Although vaginal cells and estradiol levels followed a cyclic pattern, no correlation was found between follicular diameter, estradiol and keratinized vaginal cells. We recovered 5, 1 and 4 cumulus oocyte complexes from three different individuals during weeks 19, 21, and 23 respectively. Extrusion of a polar body (1 oocyte) and germinal vesicle break down (7 oocytes) indicated progression of maturation after in vitro culture. We conclude that ultrasonography und provided a reliable method to examine xenograft survival and follicular development within the grafts. Furthermore, this technique is suitable for assessment of the efficiency of hormonal treatment and narrowing of the optimal time frame for oocyte retrieval. To our knowledge, this is the first report of the in vivo development of early antral follicles in mammalian species.     

Assessment of microbial biocontrol agent (BCA) viability to mechanical and thermal stress by simulating spray application conditions

Background

In order to improve the biological control agent (BCA) efficacy, stress factors threatening the viability of microorganisms during spray application need to be determined. The effect of spray mixture temperature and exposure time on Trichoderma harzianum T 22 and Bacillus amyloliquefaciens QST713 viability were tested. Concurrently the combined effect of mechanical and thermal stress effect on BCA viability were tested at two initial spray mixture temperatures (14 and 25 °C) by simulating a spray application using airblast sprayers featured by different tank capacity and a spray liquid circuit (without and with hydraulic agitation system). To assess the BCA microorganism viability, spray mixture samples were collected at time intervals along trials and plated to count the colony forming units (CFU).

Results

The critical temperature threshold that inhibited BCA viability was 35 °C with 30 min of exposure. The sprayer type, the initial temperature of the spray mixture and the temperature increment during the trials significantly decreased the number of CFU recovered. When simulating a spray application, the spray mixture temperature increase rate was determined mainly by the residual amount of spray mixture in the tank. Even if the tank capacity does not substantially affect the final temperature reached by the spray mixture, the higher residual spray mixture in bigger tanks can expose the BCAs for a longer time to critical temperatures.

Conclusions

Experimental trials allowed us to identify the effect of factors affecting the viability of tested BCAs, providing information about the actual chance to guarantee the biological efficacy of BCA treatments. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

Living on the edge: morphological and behavioral adaptations to a marginal high-elevation habitat in an arboreal mammal

Habitats are characterized by different local environmental conditions that influence both behavior and morphology of species, which can result in habitat-dependent phenotypic differences among animals living in heterogeneous environments. We studied 3 alpine populations of Eurasian red squirrels (Sciurus vulgaris), 1 living in a marginal high-elevation habitat at the edge of the species’ altitudinal distribution, and 2 occurring in higher-quality habitats. Here, we investigated whether squirrels living in the marginal area differed in 2 morphological parameters (body size and body mass) and/or in the expression of 4 personality traits estimated with an open field test and a mirror image stimulation test (activity, exploration, activity-exploration, and social tendency). Furthermore, we tested whether within-individual variance of the traits (behavioral plasticity) was higher in the edge habitat. Male squirrels in the edge habitat were smaller and weighed less than in the other study areas, while among females, size–habitat relationships were less marked. These sex-specific patterns were explained by a strong association between body mass and reproductive success in female squirrels. Squirrels in the marginal habitat were more active, explorative, and had a more social personality than in the other habitats. However, in contrast to our predictions, behavioral plasticity was smaller in the marginal habitat, but only for the trait exploration. Our results suggest that animals choose the habitat that best fits their personality, and that habitat-related differences in selective pressures may shape animals’ morphology.     

A comparison of soil- and canopy temperature-based methods for the early detection of water stress in a simulated patch of pasture

This paper evaluates the sensitivity of two different methods of water stress detection in a simulated patch of pasture grown in a greenhouse. The performance of two indices, based respectively on canopy temperature and soil water content values — the latter gauged by means of a time domain reflectometry (TDR) system, was assessed against actual evapotranspiration, measured by a very accurate weighing system. Both methods were able to detect water shortage by the time transpiration was reduced to some 80% of its potential value. The soil-based index, however, relied on the estimate of root water extraction rate, which may not be known. It is concluded that detection of water shortage by means of a canopy temperature-based stress index is to be preferred to measuring soil water deficits by time domain reflectometry, despite the accuracy of the TDR-based soil water content estimate.     

Enhancement of alkalinity tolerance in two cucumber genotypes inoculated with an arbuscular mycorrhizal biofertilizer containing Glomus intraradices

The aim of the present study was to determine whether arbuscular mycorrhizal (AM) inoculation with a biofertilizer containing clays as granular carriers, leek root pieces and Glomus intraradices spores could improve alkalinity tolerance of two cucumber genotypes, and to study the changes induced by AM at agronomical and physiological level. A greenhouse experiment was carried out to determine yield, growth, fruit quality, net photosynthesis (A_CO2), electrolyte leakage, and mineral composition of two cucumber (Cucumis sativus L.) genotypes (hybrid “Ekron” or open-pollinated variety “Marketmore”) with inoculated and noninoculated arbuscular mycorrhizal biofertilizer. Plants were supplied with nutrient solutions at two pH values (6.0 or 8.1). The high pH nutrient solution had the same basic composition with an additional 10 mM NaHCO₃ and 0.5 g l⁻¹ CaCO₃. The percentage root colonization was higher in “Marketmore” (21.8%) than “Ekron” (12.7%). Total and marketable yield and total biomass were significantly higher by 189%, 213%, and 77%, respectively, with Ekron in comparison to those recorded with Marketmore. The highest crop performance with Ekron in comparison to Marketmore was due to the improved nutritional status (higher N, P, K, Ca, Mg, Fe, Mn, and B), higher leaf area, and net photosynthesis. Increasing the concentration of NaHCO₃ from 0 to 10 mM in the nutrient solution significantly decreased yield, plant growth, A_CO2, N, P, Fe, Cu, Zn, Mn, and B concentration in leaf tissue, whereas the electrolyte leakage increased. The inoculated plants under alkaline conditions had higher total, marketable yield, and total biomass than noninoculated plant. Mycorrhizal cucumber plants grown under alkaline conditions had a higher macronutrient concentration in leaf tissue compared to noninoculated plants. The highest yield and biomass production in inoculated plants seems to be related to the capacity of maintaining higher net A_CO2 and to a better nutritional status (high P, K, Mg, Fe, Zn, and Mn and low Na accumulation) in response to bicarbonate stress with respect to −AM plants.     

Factors Affecting the Growth of Microalgae on Blackwater from Biosolid Dewatering

This paper discusses the possibility of including the culturing of microalgae within a conventional wastewater treatment sequence by growing them on the blackwater (BW) from biosolid dewatering to produce biomass to feed the anaerobic digester. Two photobioreactors were used: a 12 L plexiglas column for indoor, lab-scale tests and a 85 L plexiglas column for outdoor culturing. Microalgae (Chlorella sp. and Scenedesmus sp.) could easily grow on the tested blackwater. The average specific growth rate in indoor and outdoor batch tests was satisfactory, ranging between 0.14 and 0.16 day^?1. During a continuous test performed under outdoor conditions from May to November, in which the off-gas from the combined heat and power unit was used as the CO₂ source, an average biomass production of 50 mgTSS L^?1 day^?1 was obtained. However, statistical analyses confirmed that microalgal growth was affected by environmental conditions (temperature and season) and that it was negatively correlated with the occurrence of nitrification. Finally, the biochemical methane potential of the algal biomass was slightly higher than that from waste sludge (208 mLCH₄ gVS^?1 vs. 190 mLCH₄ gVS^?1).     

Sap flow in ‘Hass’ avocado trees on two clonal rootstocks in relation to xylem anatomy

The rates of sap flow and xylem vessel features were studied in two-year-old nongrafted and grafted avocado (Persea americana Mill.) trees. Daily sap flow rates were measured with heat and balance stem gauges in clonal Duke 7 (D7) and Toro Canyon (TC) trees and ‘Hass’ clonal scions grafted onto clonal D7 (H/D7) and TC (H/TC) rootstocks. Vessel features as size, number and total vessel area were determined histologically in the stem of the scion and rootstock and the roots of the grafted trees. Significant differences in the sap flow rate were found among the rootstocks, where D7 had a 29% higher sap flow rate than did TC (grafted and nongrafted trees). There were no differences among xylem vessel features in the stems of any of the varieties. However in the roots, D7 had wider and fewer vessels then TC do. Also, D7 had a 19% higher total vessel area than TC. These results suggest that the differences in water consumption of ‘Hass’ on different rootstocks may be associated with differences in the efficiency of the roots to absorb water across conductive tissue which may be linked to differences in the area of xylem vessels in the root.     

Conserving indigenous crayfish: stock assessment and habitat requirements in the threatened Austropotamobius italicus

• 1. As part of the Austropotamobius pallipes species complex, the crayfish Austropotamobius italicus is a species of community interest whose preservation requires the designation of Special Areas of Conservation (SACs) (Annex II, EU Habitats Directive). This study aimed at (1) assessing the conservation status of this threatened indigenous species by stock assessment in central Italy and (2) identifying some aspects of its elective habitat.
• 2. Surveys were conducted in nine streams harbouring A. italicus (streams WI) and in 10 streams where crayfish populations became extinct at least 5 years before the study (streams WO).
• 3. The results confirmed that A. italicus is a K‐selected species, with a relatively slow growth rate (males: 0.34; females: 0.37) and a long life expectancy (males: 8.2 years; females: 7.8 years). The extant populations are healthy, showing balanced sex‐ratios and well structured age‐class compositions. Mortality is mainly due to fishing, which is illegal in Tuscany.
• 4. Principal Components Analyses showed that the streams WI and WO differ in the abundance of allochthonous plant detritus but not in the taxonomic composition of their macroinvertebrate communities. Age classes were found to be spatially segregated, juveniles mainly using cobbles as substrates and adults seemingly avoiding them.
• 5. The loss of the pristine riverine landscape seems to have been responsible, together with illegal fishing, for the local extinction of the species. As a consequence, retaining, enhancing, and restoring the habitat and its complexity are required for the preservation of A. italicus.
• 6. The designation of SACs might help in this endeavour if accompanied by programmes aimed at publicizing the need for conservation of this species. Unfortunately, crayfish‐focused projects supported by LIFE in Italy since 1992 (4%) and the SACs involved (1.4%) have been relatively few, despite the poor conservation status of this species and its well recognized ecological role.

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