Thymic structural changes in relation to seasonal cycle and testosterone administration in wall lizard Hemidactylus flaviviridis (Ruppell)

Light microscopic and ultrastructural studies of thymus in wall lizard showed remarkable season dependent structural changes. In winter, the thymus was involuted and its cortico-medullary differentiation was not distinct. Thymocytes were sparsely distributed. The epithelial cells exhibited atrophic features such as an appreciable decrease in the nuclear-cytoplasmic ratio and accordingly reduction in cell organelles. The reconstruction of thymus commenced during spring and it became fully developed with marked delineation of cortico-medullary regions during summer. The thymus was then densely populated with thymocytes and epithelial cells showed voluminous cytoplasm having numerous cell organelles. The thymus regression started again by the beginning of autumn. The results suggest that the thymic development in wall lizard have inverse relationship with the androgen level, as the testicular steroidogenic activity was seen maximum during winter and least in summer. This assumption gets support by castration and testosterone replacement experiments. Castration of lizards during winter resulted in profound development of thymus with an appreciable increase in thymocytes mainly in the cortex region . The cortex became delineated from the medulla. Following testosterone treatment, the thymus underwent regression and was comparable to testis-intact lizard's thymus during winter season. After withdrawal of testosterone treatment, the thymus exhibited dense lymphoid and thymocyte population with a demarcation of cortico-medullary regions and sub-cortical region was regenerated.     

cis-Polyisoprene Synthesis in Guayule Plants (Parthenium argentatum Gray) Exposed to Low, Nonfreezing Temperatures

Exposure of guayule plants (Parthenium argentatum Gray) to 6 months of a night temperature of 7°C results in a 2-fold stimulation of cis-polyisoprene (rubber) formation over that of control plants exposed to 21 to 24°C night temperature. Control and cold-treated plants contained 2.18% and 5.69% rubber, respectively. Examination of the stem apices by transmission electron microscopy showed extensive formation of rubber particles in the cold-treated plants compared to the control plants. The rubber particles in guayule are formed in the cytoplasm and fuse to form large globular deposits. The surface area of the rubber particles and globules range from 4 × 10⁻⁶ to 2.9 × 10⁻³ square micrometers. The deposition of rubber in the cytoplasm of the cortical parenchyma cells differs from rubber deposition in the vacuoles of laticifers of Asclepias syriaca. Electron micrographs of stem cortical parenchyma in control plants show mature cells with large central vacuoles, thin layers of parietal cytoplasm, and smaller numbers of rubber particles. Radioactive acetate and mevalonate are incorporated into rubber at a faster rate in stem slices from cold-treated plants compared to slices from control plants. A faster rate of these reactions may account for the increase in rubber synthesis in the cold-treated plants.     

A Study of Differential Expression of Testicular Genes in Various Reproductive Phases of Hemidactylus flaviviridis (Wall Lizard) to Derive Their Association with Onset of Spermatogenesis and Its Relevance to Mammals

Testis of Hemidactylus flaviviridis, commonly known as Indian wall lizard, displays a lack of cellular and metabolic activity in regressed phase of testis during non-breeding season of the year. Retracted Sertoli cells (Sc), fibroid myoid cells and pre-meiotic resting spermatogonia are observed in such testis. This situation is akin to certain forms of infertility in men where hormone supplementation fails to generate sperm despite the presence of Sc and germ cells (Gc) in testis. In testis of lizard, spermatogenesis is reinitiated upon increased level of hormones during appropriate season (phase of recrudescence). Study of genes associated with generation of sperm, from regressed adult testis in lizard, may provide valuable information for understanding certain forms of male idiopathic infertility. Subtractive hybridization using testicular RNA obtained from the regressed and active phases of lizard reproductive cycle led to identify eight partial mRNA sequences that showed sequence homology with mice genes. We further evaluated the gene expression prolife by real-time PCR in three different reproductive phases of H. flaviviridis: regressed (pre-meiotic), recrudescent (meiotic) and active (post meiotic), for comparison with the corresponding testicular phases found in testis of 5 days (pre-meiotic), 20 days (meiotic) and 60 days (post-meiotic) old mouse. This is the first report where genes associated with progression of spermatogenesis during active phase, which follows a regressed state of adult testis, were identified in lizard and found to be conserved in mouse. Six important genes, Hk1, Nme5, Akap4, Arih1, Rassf7 and Tubb4b were found to be strictly associated with active spermatogenesis in both mouse and lizard. Factors interfering with the expression of any of these genes may potentially abrogate the process of spermatogenesis leading to infertility. Such information may shed light on unknown causes of idiopathic male infertility.     

Light Regulation of Peridinin-Chlorophyll a-Protein (PCP) Complexes in the Dinoflagellate, Glenodinium sp. : Use of Anti-Pcp Antibodies to Detect Pcp Gene Products in Cells Grown in Different Light Conditions

As a step toward developing the tools needed to study the molecular bases of light regulation of gene expression in dinoflagellates, light-harvesting peridinin-chlorophyll a-protein (PCP) complexes from Glenodinium sp. were purified and used to generate anti-PCP antibodies. Affinity purified anti-PCP antibodies were isolated from the crude anti-PCP antiserum resulting in improved specificity of immune reactions. The affinity purified anti-PCP antibodies were shown to react strongly and specifically with all major isoforms of PCP complexes in Glenodinium sp. cells, and were used to assess qualitative changes in the levels of PCP gene products in cells grown under different light conditions. Western blot analysis revealed a two- to three-fold increase in detectable PCP apoprotein in low light compared to high light grown cells. In vitro translation reactions supplied with total RNA from high and low light grown Glenodinium sp. cultures also showed an approximate twofold increase in translatable PCP mRNAs in low light grown cells as determined by immunoprecipitation of the primary translation products with affinity purified anti-PCP antibodies. In addition, PCP apoproteins appear to be encoded as larger pre-proteins, since the major immunoprecipitated products from in vitro translation are 23 and 22 kilodaltons, while mature PCP apoproteins are 15.5 kilodaltons. The parallel increases in PCP apoprotein and translatable PCP mRNAs indicate that light regulation of PCP complexes occurs at the level of PCP mRNA abundance.     

Effect of Four Sowing Date Environments on Growth, Development and Yield Potentials of 15 Pearl Millet Cultivars (Pennisetum americanum L Leeke) During Autumn-Winter Seasons in Marin, N.L., Mexico

A study has been undertaken on the growth, development, andyield potentials of 15 pearl millet cultivars showing a largegenetic variability in growth parameters in different sowingenvironments Sowing date had a significant effect on growthstages (GS1, GS2, GS3), thermal units accumulated in respectivegrowth stages, days to flowering, and yield components of thepearl millet cultivars Significant genotype x sowing date interactionswere also observed for the majority of the variables mentioned. A decline in both temperature and length of photopenod oversuccessive sowing dates from July to September had a drasticeffect on phenology and yield potentials of the pearl milletcultivars. Higher grain yield in the July sowing experiment, compared tothose for other sowing dates, could be related to a longer photopenod(> 13 h), higher temperatures, and a significant differencebetween day and night temperatures. Key words: Environment, growth, yield potentials, thermal units, pearl millet     

Temperatures in Pigs During 3 T MRI Temperatures,Heart Rates,and Breathing Rates of Pigs During RF Power Deposition in a 3 T (128 MHz) Body Coil

Exposure to radiofrequency (RF) power deposition during magnetic resonance imaging (MRI) induces elevated body‐tissue temperatures and may cause changes in heart and breathing rates, disturbing thermoregulation. Eleven temperature sensors were placed in muscle tissue and one sensor in the rectum (measured in 10 cm depth) of 20 free‐breathing anesthetized pigs to verify temperature curves during RF exposure. Tissue temperatures and heart and breathing rates were measured before, during, and after RF exposure. Pigs were placed into a 60‐cm diameter whole‐body resonator of a 3 T MRI system. Nineteen anesthetized pigs were divided into four RF exposure groups: sham (0 W/kg), low‐exposure (2.7 W/kg, mean exposure time 56 min), moderate‐exposure (4.8 W/kg, mean exposure time 31 min), and high‐exposure (4.4 W/kg, mean exposure time 61 min). One pig was exposed to a whole‐body specific absorption rate (wbSAR) of 11.4 W/kg (extreme‐exposure). Hotspot temperatures, measured by sensor 2, increased by mean 5.0 ± 0.9°C, min 3.9; max 6.3 (low), 7.0 ± 2.3°C, min 4.6; max 9.9 (moderate), and 9.2 ± 4.4°C, min 6.1, max 17.9 (high) compared with 0.3 ± 0.3°C in the sham‐exposure group (min 0.1, max 0.6). Four time‐temperature curves were identified: sinusoidal, parabolic, plateau, and linear. These curve shapes did not correlate with RF intensity, rectal temperature, breathing rate, or heart rate. In all pigs, rectal temperatures increased (2.1 ± 0.9°C) during and even after RF exposure, while hotspot temperatures decreased after exposure. When rectal temperature increased by 1°C, hotspot temperature increased up to 42.8°C within 37 min (low‐exposure) or up to 43.8°C within 24 min (high‐exposure). Global wbSAR did not correlate with maximum hotspot. Bioelectromagnetics. 2021;42:37–50. © 2020 The Authors. Bioelectromagnetics published by Wiley Periodicals LLC on behalf of Bioelectromagnetics Society     

Bioavailability of 2, 4, 6-Trinitrotoluene (TNT) to Earthworms in Three Different Types of Soils in China

To study the effects of aging time (the length of time when contaminants are sequestered in soil) and soil properties on TNT bioavailability in soil, earthworms (Eisenia fetida) were exposed to three types of soils (fluvo-aquic soil, loessal soil, and black soil) contaminated by TNT for 7, 14, 21, 28, 35, and 42 days. The Earthworm-Soil Accumulation Factor (ESAF) of TNT and soil properties were analyzed. The ESAFs in black soil were significantly lower than those in fluvo-aquic soil and loessal soil (P < 0.05). In loessal soils, the ESAF increased with aging time, while that in black soils decreased. The ESAF of TNT had a significantly negative correlation with soil organic matter content, clay contents, and cation exchange capacity, which were the main factors affecting the TNT bioavailability in soils (P < 0.01). There was more quartz and feldspar in black soil, as well as more particles and micropores on the surface, which resulted in the easy adsorption and lower bioavailability of TNT. In conclusion, TNT bioavailability in soils is affected by aging time, soil physical and chemical properties, and mineral and surface properties, which must be considered when biotreatment for TNT in soils is applied.     

Thermal Requirements and Parasitism Capacity of Trissolcus brochymenae (Ashmead) (Hymenoptera: Scelionidae) Under Constant and Fluctuating Temperatures, and Assessment of Development in Field Conditions

In order to understand the relative importance of Trissolcus brochymenae , a common egg parasitoid of the predatory stinkbug Podisus nigrispinus in areas where this predator is released, the thermal requirements and developmental periods (egg to adult) at constant (17, 20, 25, 28 and 32°C) and fluctuating (10-20, 13-23, 15-25, 17-27, 20-30 and 25-35°C) temperatures, and the effect of constant and fluctuating temperatures systems on the longevity and parasitism capacity of T. brochymenae were investigated. Based on thermal requirements of the parasitoid and field day/night temperature variation in the regions where P. nigrispinus was released, we calculated monthly and yearly number of generations of the parasitoid. Parameters of biological and thermal requirements of T. brochymenae were not affected when the insects were reared under constant or fluctuating temperatures. It was shown that males have a shorter developmental period and lower thermal requirements than females. The lowest parasitism capacity and shortest longevity of T. brochymenae were observed under fluctuating temperature regimes of 10-20oC and 25-35°C. A higher parasitism capacity was obtained under a 20-30°C regime (96.0 ±33.6 offspring per female), while longevity was longer at a constant temperature of 27°C (17.6 ±0.6 days). T. brochymenae showed a continuous development during all seasons through the year under field conditions, accomplishing 2.7, 2.4, 2.9 generations per month in the CAF, Pains, and Refloralje areas. An average of 26.4 and 25.8, 25.8 and 25.3, and 24.7 and 23.6 generations per year under constant and fluctuating temperatures systems was estimated for the CAF, Pains, and Refloralje areas, respectively. No significant difference between thermal systems in each area was observed; however, a significantly smaller number of generations per year were estimated to occur in the Refloralje area. Implications of these results for the forecasting of parasitoid population development and its impact on the host stinkbug predator are discussed.     

Germination, Radial Growth, and Sporulation of Beauveria bassiana and Metarhizium anisopliae Isolates and Their Virulence to Chilo partellus (Lepidoptera: Pyralidae) at Different Temperatures

The effect of temperature regimes on conidia germination, radial growth and virulence of Beauveriabassiana and Metarhizium anisopliae against the spotted stalk borer Chilo partellus was investigated with Ethiopian isolates. Conidia germination, radial growth and sporulation of all isolates were retarded at 15 and 35°C. A suitable temperature range for the isolates was between 20 to 30°C. Conidia germination was less tolerant of low temperature (15°C) than radial growth. Radial growth and sporulation reacted differently to temperature. At both 25 and 30°C, all isolates induced 100% mortality to C. partellus larvae in six days. The LT₅₀ decreased for the isolates with increasing temperature.     

Natural Hybridization and Introgression between Ligularia cymbulifera and L. tongolensis (Asteraceae,Senecioneae) in Four Different Locations

Natural hybridization has been considered to represent an important factor influencing the high diversity of the genus Ligularia Cass. in the Hengduan Mountains, China. Natural hybridization has been confirmed to occur frequently in Ligularia. To date, however, it has been demonstrated only within a single population. In this paper, we present evidence of natural hybridization in Ligularia from four different locations. The internal transcribed spacer (ITS) region of the nuclear ribosomal DNA and three chloroplast intergenic spacers (trnK-rps16, trnL-rpl32 and trnQ-5''rps16) of 149 accessions of putative hybrids and their putative parents (L. cymbulifera and L. tongolensis) were analyzed for evidence of hybridization. The ITS data clearly distinguished two putative parental species and sympatric L. vellerea and supported the hypothesis that those morphological intermediates were products of natural hybridization between L. cymbulifera and L. tongolensis. Moreover, several identified morphological parents were actual introgressed products. Because of hybridization and introgression, chloroplast DNA sequences generated a poorly resolved network. The present results indicate that varying degrees of hybridization and introgression occur differently depending on the habitat context. We conclude that gene flow caused by natural hybridization in Ligularia indeed plays an important role in the species diversity.     

The Expression of Three Opsin Genes from the Compound Eye of Helicoverpa armigera (Lepidoptera: Noctuidae) Is Regulated by a Circadian Clock,Light Conditions and Nutritional Status

Visual genes may become inactive in species that inhabit poor light environments, and the function and regulation of opsin components in nocturnal moths are interesting topics. In this study, we cloned the ultraviolet (UV), blue (BL) and long-wavelength-sensitive (LW) opsin genes from the compound eye of the cotton bollworm and then measured their mRNA levels using quantitative real-time PCR. The mRNA levels fluctuated over a daily cycle, which might be an adaptation of a nocturnal lifestyle, and were dependent on a circadian clock. Cycling of opsin mRNA levels was disturbed by constant light or constant darkness, and the UV opsin gene was up-regulated after light exposure. Furthermore, the opsin genes tended to be down-regulated upon starvation. Thus, this study illustrates that opsin gene expression is determined by multiple endogenous and exogenous factors and is adapted to the need for nocturnal vision, suggesting that color vision may play an important role in the sensory ecology of nocturnal moths.     

Patterns of Fluctuating Asymmetry and Shape Variation in Chironomus riparius (Diptera,Chironomidae) Exposed to Nonylphenol or Lead

Deformities and fluctuating asymmetry in chironomid larvae have been proposed as sensitive indicators of biological stress and are commonly used to assess the ecological impact of human activities. In particular, they have been associated in Chironomus riparius, the most commonly used species, with heavy metal and pesticide river pollution. In this study, the effect of lead and 4-nonylphenol on mouthpart morphological variation of Chironomus riparius larvae was investigated by traditional and geometric morphometrics. For this purpose, first to fourth instar larvae were exposed to sediment spiked with lead (from 3.0 to 456.9 mg/kg dry weight) or 4-NP (from 0.1 to 198.8 mg/kg dry weight). Mentum phenotypic response to pollutants was assessed by four parameters: (1) the frequency of deformities, (2) fluctuating asymmetry of mentum length, (3) fluctuating asymmetry of mentum shape and (4) the mentum mean shape changes. Despite the bioaccumulation of pollutants in the chironomid’s body, no significant differences between control and stressed groups were found for mouthpart deformities and fluctuating asymmetry of mentum length. Slight effects on mentum shape fluctuating asymmetry were observed for two stressed groups. Significant mean shape changes, consisting of tooth size increase and tooth closing, were detected for lead and 4-NP exposure respectively. Those variations, however, were negligible in comparison to mentum shape changes due to genetic effects. These results suggest that the use of mentum variation as an indicator of toxic stress in Chironomus riparius should be considered cautiously.     

Free Amino Acid Profile in Blood Plasma of Bats (<Emphasis Type="Italic">Myotis dasycneme</Emphasis> Boie, 1825) Exposed to Low Positive and Near-Zero Temperatures

We analyze here for the first time the plasma free amino acid profile in pond bats (Myotis dasycneme Boie, 1825) living in the boreal Ural region and exposed experimentally to low positive and near-zero temperatures during their preparation for hibernation. Pond bats were caught in their mass habitation territory in the Middle Ural near the Smolinsky cave (N 56°28’, E 61°37’) in the third decade of September 2015. Qualitatively, blood plasma in pond bats contains 21 amino acids. In a model experiment carried out on pre-hibernating animals at a regular hibernation temperature (0–2°C), the total plasma pool of free amino acids increased significantly by 42% (irrespective of sex) and reached 1561.4 ± 112.6 μmol/L (p = 0.01). Under these experimental conditions, the fraction of glucogenic amino acids rose by 34% (p = 0.01) and that of essential ones by 80% (p = 0.001). Both in control and experimentally cooled pre-hibernating animals, the plasma was found to lack tryptophan, suggesting its utilization as a substrate in the synthesis of serotonin, a biogenic amine directly involved in the maintenance of hypothermia and hypometabolism in these chiropterans.     

肇庆南草蜥形态、食性及运动表现的两性差异

通过测量头、尾、体和胃检,研究肇庆南草蜥Takydromus sexlineatus个体发育过程中两性异形和食性差异。南草蜥成体个体两性大小无显著差异,雄性头部显著大于雌性,两性头部大小异形可能是受到性选择压力的结果。雌雄个体食物生态位重叠度较高,两性生态位差异微弱,食性差异与两性头部异形无明显相关性。通过设计13种不同的环境温度,研究体温变化对南草蜥两性个体运动能力表现的影响。结果显示环境温度通过影响体温而影响南草蜥的运动表现,两性个体疾跑速均具有在低体温范围内随体温升高而加快、在高体温范围内随体温升高而降低的模式。在多数测试温度下,雄体的疾跑速均略大于雌体,但两者平均值在统计上无显著差异。体温对南草蜥的最大持续运动距离和停顿次数的影响显著,两性个体的疾跑速和最大持续运动距离呈显著正相关。雄性和雌性分别在26℃和30℃具有最佳的运动表现。     

Circadian Rhythm of Liver Parameters (Cellular Structures, Mitotic Activity, Glycogen and Lipids in Liver and Serum) During Three Consecutive Cycles in Phenobarbital-Treated Rats

The circadian rhythm of gastric content, serum alkaline phosphatase (alk.P.), serum lipids, body weight (wt), relative (rel.) liver wt, cellular structures (by light- and electron-microscopy), mitotic activity of hepatocytes, glycogen content, protein and lipids in liver was studied in 180 male Sprague-Dawley rats orally treated at 0830-1030 with 50 mg/kg phenobarbital (PB) for 7 days. Thereafter, five PB-treated males and five controls each were studied at 4-hr intervals at 0600, 1000, 1400, 1800, 2200 and 0200 on 3 consecutive days. The lighting schedule in the colony was 12:12 = light/dark (light from 0600 to 1800). Following the rhythm of gastric emptying, the rel. liver wt showed a clear circadian rhythm with a peak at 0800. The rel. liver wt was raised in PB-treated rats at all times of the day. The circadian rhythm of cellular structures was closely related to the hepatic glycogen content which exhibited a clear rhythm with the peak also at 0800, but lowered values were found in PB-treated rats. The mitotic activity of hepatocytes was significantly increased in PB-treated rats but displayed the same circadian rhythm as controls with peaks at noon and troughs at midnight. The well-known hypertrophy of the smooth endoplasmic reticulum in PB-treated rats was not found at 0600, but was fully developed at 1400 and 2200. PB-treatment increased significantly the liver content of cholesterol, triglycerides and phospholipids. Liver cholesterol showed a clear circadian rhythm with peaks at 1800. No rhythm of liver protein, triglycerides and phospholipids was observed. In serum, levels of cholesterol were significantly elevated, those of triglycerides and alk.P. significantly lowered, while those of phospholipids were not affected by the treatment. The three serum lipids, alk.P. and beta-lipoprotein exhibited a clear circadian rhythm, while serum glucose and non-esterified fatty acids did not.