Seasonal Environmental Changes Research Articles

Differential responses of non-human primates to seasonal temperature fluctuations.

Non-human primates (NHPs) can adapt to conditions outside of their natural habitat and climatic ranges but this can be influenced by inherent evolutionary traits or plasticity of species that evolved in diverse environmental conditions. In this study, we investigated how five species of NHPs that have natural distributions across a range of climatic conditions responded to seasonal temperature changes in a captive environment. The activity levels of NHPs were affected by temperature changes over the season, where activity levels were generally reduced at the lower and higher temperature ranges. Species that are naturally found within narrower and warmer climatic ranges, compared to those found in colder environments with wider fluctuations in temperature, showed more marked changes in activity levels in response to temperature changes. In lower temperature conditions, three out of five species showed significantly lower activity levels; whereas in higher temperature conditions, the activity levels of all species did not significantly decrease. The frequency of thermoregulation behaviours was higher, and use of artificial thermoregulatory sources lower, for species that did not substantially adjust their activity levels in different temperature conditions. Our results suggest that NHPs largely retained the evolutionary traits related to thermoregulation, according to the different ambient conditions they evolved in and may have low behavioural plasticity in adapting to conditions outside of their natural ranges. These results provide insights for improving conservation and captive management and may have implications for understanding NHP resilience to the increasing impact of global climate change.

CCT domain-containing genes in cereal crops: flowering time and beyond.

The review summarizes the functions of the plant special transcription factors CCT family genes in multiple traits and discusses the molecular breeding strategies with CCT family genes in the future. Plants integrate circadian clock and external signals such as temperature and photoperiod to synchronize flowering with seasonal environmental changes. This process makes cereal crops including short-day crops, such as rice and maize, and long-day crops, such as wheat and barley, better adapt to varied growth zones from temperate to tropical regions. CCT family genes involve circadian clock and photoperiodic flowering pathways and help plants set a suitable flowering time to produce offspring. Beyond the flowering time, CCT family genes in cereal crops are associated with biomass and grain yield. Moreover, recent studies showed that they also associate with photosynthesis, nutrition use efficiency and stress tolerance. Here, we systematically review the progress in functional characterization of CCT family genes in flowering, geographical adaptation and grain yield formation, raise the core questions related to their molecular mechanisms and discuss how to practice them in genetic improvement in cereal crops by combining gene diagnosis and top-level design.

Risk sensitivity in Beverton–Holt fishery with multiplicative harvest

AbstractWe present a steady‐state threshold risk analysis framework for exploited populations following the Beverton–Holt recurrence. The Beverton–Holt model is widely applied in the assessment of species biomass and fitted to experimental data to obtain a suitable range of parameter values. To account for the uncertainty in these parameter values, such as the growth rate, we analyze the probability of the steady‐state harvested population falling below a critical threshold. More precisely, the Beverton–Holt equation with constant multiplicative survival, constant carrying capacity, and constant growth rate is considered. Under the assumption of a stochastic distributed proliferation rate, we analyze the risk of the steady‐state population falling below a specified threshold, under constant harvest. We demonstrate a characteristic sensitivity property of that risk, that we refer to as “instability wedge,” in the parameter space. We continue the study by assuming a 2‐periodic carrying capacity, representing seasonal changes in the population's environment. Again, we demonstrate the risk sensitivity phenomenon. Although the growth rate was chosen to have a uniform distribution in presented examples, the framework extends to other probability distributions.

A multi-biomarker approach using integrated biomarker response to assess the effect of pH on triclosan toxicity in Pangasianodon hypophthalmus (Sauvage, 1878)

Application of biomarkers is an effective approach for a better understanding of varying toxicity in aquatic organisms during the seasonal and diurnal changes in the natural environment. This report describes the toxicity of sub-lethal concentrations of triclosan (TCS) at different pH (6.5, 7.5 and 8.5) based on selected biomarkers related to oxidative stress, metabolism and genotoxicity in Pangasianodon hypophthalmus. The 96 h LC50 of TCS for P. hypophthalmus was lower at pH 6.5 when compared to higher pH. The sub-lethal concentration of TCS exhibited a significant decrease in hematological parameters related to complete blood counts except for total leukocyte count (TLC), mean cell haemoglobin concentration (MCHC) and red cell distribution width (RDW). Multivariate data analysis showed a significant interaction of TCS and pH in metabolizing enzymes like glutamic oxaloacetate transaminase (GOT), glutamic pyruvic transaminase (GPT), Lactate dehydrogenase (LDH), antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT) and glutathione-s-transferase (GST) and neurotransmitter enzyme acetylcholinesterase (AChE). A significant increase in DNA damage and micronuclei frequency in liver and blood cells of TCS exposed fish at pH 6.5 indicate that the TCS exposure has pronounced effects on genetic materials. The findings of present study establish that enzymes like SOD, LDH, GOT, AChE, DNA damage and micronuclei frequency can be successfully deployed as biomarkers for the assessment of toxicity of TCS in fish.

Benthic foraminifera as proxies of marine influence in the Orosei marine caves, Sardinia, Italy

Abstract As a result of their location at the boundary between marine and continental domains, marine caves are affected by wide spatial and seasonal environmental changes. Only recently have benthic foraminifera been recognized as reliable indicators for the ecological zonation of these environments. The present study is focused on two marine caves of the Orosei Gulf, Sardinia, Italy: Bue Marino and Bel Torrente. It investigates the spatial and seasonal variability of benthic foraminiferal assemblages relative to sediment grain size and water parameters (temperature, salinity, pH, and dissolved oxygen) collected during two campaigns in August 2014 and April 2015. The results from 2014 have been partially published. Based on a comparison of the results of the two campaigns, the considerable reduction of foraminiferal abundance in Bel Torrente was deduced to occur because of the strong freshwater flows occurring during the rainy season; in Bue Marino, the less severe water flow allowed the identification of both living and dead foraminifera, although strongly reduced in number. These identifications allowed benthic foraminifera to be used to define the ecological zonation. Entrance, confluence, and transitional ecozones were identified in Bue Marino cave on the basis of species abundance. The second ecozone, not recognized in 2014, was correlated with plant debris at the confluence of the two cave branches. The other two ecozones, which are characterized by the faunal shift from hyaline‐ to agglutinated‐prevalent assemblages, were attributed to the gradient of abiotic parameters detected from the outer to the inner portions of the cave. In both campaigns the same ecozones were recognized in terms of species composition, with exceptions being found to different extents as a result of seasonal variability. As the distribution of foraminiferal ecozones is conditioned by a decreasing gradient of marine influence, long‐term monitoring may be regarded as a promising tool for future studies on sea‐level change.

Artificial nacre-like layer using layer coating with bioinspired mesolayer insertions

The fabrication of coatings using conventional methods [e.g., physical vapor deposition (PVD) and/or pulsed laser deposition (PLD)] usually creates clear interfaces between the edges. It is challenging to increase the toughness by adding soft materials into hard materials to reinforce the structures using architectural design. In this study, we determined that by adding soft materials into hard materials, we can simulate nacre, which results in stronger coatings. However, the compatibility of materials needs to be considered (i.e., the bonding of organic/inorganic components to each other). Titanium dioxide (TiO2), an inorganic material, was chosen as the hard part, and polyimide (PI), an organic material, was chosen as the soft part. When we fused these two materials together to form a layer-by-layer coating, the bonding between them was not good, which degraded the mechanical performance. Nevertheless, we revaluated the differences between artificial and natural coatings. The layers in nacre smoothly change from chitins to proteins or from proteins to chitins owing to the seasonal environmental temperature changes. Inspired by this concept and by simulating nature, we created mesolayers to adhere two different materials and to enhance the coatings that are made entirely of inorganic or organic materials to create new composites using the PVD/PLD method. The mesolayers mixed with two materials at proper ratios were inserted into the organic/inorganic (PI/TiO2) interfaces as bridges to cross-link the materials and dramatically improve the mechanical performance, which is similar to the structure of natural nacre.

Variations in important water quality parameters and fish species in Thondaimanaru Lagoon, Jaffna, Sri Lanka

Thondaimanaru lagoon is one of the shallow coastal lagoons in Jaffna peninsula. The current study was conducted to assess the present status of water quality and fish species composition of this lagoon. Water sampling was conducted from July 2016 to December 2016. Nine random samples were collected monthly in order to determine water temperature, pH, salinity, Dissolved Oxygen, Total Dissolved Solids and turbidity. A smarTROLL Multi parameter (Insitu 458389) was used to measure all the parameters except turbidity, which was measured by turbidity meter (2100Q HACH). Random samples of fishes were collected once a month. One-way ANOVA was used to perform statistical analysis. Water temperature, Dissolved Oxygen, salinity, Total Dissolved Solids and turbidity showed significant variations (p 0.05) among the months. Chanos chanos, Hemirhamphus sp., Nematalosa nasus, Mugil cephalus, Liza parsia, Oreochromis mossambicus, Arius caelatus and Gerres lucidus were present throughout the study period. Results revealed that the important water quality parameters fluctuated due to seasonal environmental changes where shallow water depth of lagoon, rate of evaporation as well as precipitation had a significant influence on the water quality characteristics.

Adélie penguins’ extensive seasonal migration supports dynamic Marine Protected Area planning in Antarctica

Spatiotemporal dynamics of ecosystems can challenge the pertinence of Marine Protected Area (MPA) planning. Seasonal environmental changes are extreme in polar regions, however MPA planning in East Antarctica relies mostly on species' summer distribution only. Thirteen Adélie penguins were tracked from Ile des Pétrels (Terre Adélie), and their seasonal distribution and behaviour were compared to the proposed “D'Urville Sea-Mertz” MPA. During the phase of high food-demand preceding moult, penguins used mostly (68.4%) this proposed area. However, following autumnal sea ice extension, penguins migrated north-westwards: overall, 73% of their locations were outside the MPA proposal, and this was up to >99% during winter (in July), the season when penguins maximized their dive depth and time (August and September, respectively). This study thus supports the proposal of implementing a “krill no-take zone” policy in this MPA, in line with the pre-moult foraging of these krill predators in this area. Further protection of the year-round habitats of migratory Adélie penguins could be achieved by inter-connecting the East Antarctic MPA proposals along the ice edge during winter, thereby mirroring the ecosystem's seasonal dynamics.

Seasonality of reproduction in gilts and sows

In the wild, the pig adapts her reproductive functions according to the seasonal changes in the environment, such as the ambient temperature and availability of food. Like in other short day seasonal breeders, breeding season is favoured in the mid winter in order to provide the offspring with the best chances to survive four months later. Seasonal changes in environment are perceived mainly by the ability of the pig to recognise seasonal changes in photoperiod. This information is mediated through changes in the activity of the pineal gland to secret melatonin, essentially by the same mechanism as reported for other mammals. Stimulation of melatonin receptors located in the hypothalamus has a significant role for the release of GnRH and subsequent gonadotrophin release from the pituitary. Management and nutrition related factors determine the degree of seasonal effects on reproduction in the commercial piggery environment. Significant improvements in fertility in herds suffering from seasonal infertility are achievable by providing gilts and sows with abundant feed after mating. Attempts to alleviate the seasonal effects on fertility by applying light programs are underway and may lead to significant improvements in productivity of the domestic pig in the long run. Hormonal treatments may be somewhat effective, but not a sustainable solution to seasonal infertility. In conclusion, seasonal infertility is a photoperiod induced phenomenon that can be manipulated by changes in photoperiod and by accounting for season as a significant factor when feeding strategies are applied in commercial piggeries.

실외 실험적 온난화 및 강수 조절 하에서 토양 수분과 소나무 묘목의 생리 및 생장 반응 간의 관계

We investigated the changes in soil water and physiological and growth responses of Pinus densiflora seedlings under open‐field experimental warming and precipitation manipulation. In April 2013, we planted 2‐year‐old P. densiflora seedlings at 2 temperature levels (control, +3°C warmed) × 3 precipitation levels (control, ‐30% decreased, +30% increased) × 3 replicates (n=18). Soil water content (SWC), net photosynthetic rate (PSUBn/SUB), stomatal conductance (gSUBs/SUB), transpiration rate (E), intrinsic water use efficiency (iWUE), and total chlorophyll content (Tchl.) were measured in April, May, July, and August 2015, and the growth rate was calculated for April 2015‐March 2016. SWC significantly decreased by warming and precipitation manipulation. The rate of change in SWC was 12.17% under warming, but 5.13% and 6.53% under decreased and increased precipitation, respectively. PSUBn/SUB, gSUBs/SUB, and E decreased significantly by 17.09%, 18.25%, and 16.76% under warming, while only E changed by ‐5.29% and 20.28% under decreased and increased precipitation, respectively. There were no significant changes in iWUE or Tchl. by warming or precipitation manipulation. SWC was correlated with PSUBn/SUB, gSUBs/SUB, and E in April and May, and Pn in July, but was not correlated with any physiological properties in August. Seedling growth rates of root collar diameter and height were not changed despite the decrease in PSUBn/SUB related to warming. In this study, the effect of warming on physiological responses was greater than that of precipitation manipulation, and PSUBn/SUB decreased due to stomatal closure induced by soil water reduction under warming. These responses changed with seasonal environmental changes.

Multiannual decrement of nutrient concentrations and phytoplankton cell size in a Mediterranean reservoir

Reservoirs are primary water resources for many uses in the Mediterreanean region and need dedicated studies for understanding the complexity of their dynamics particularly vulnerable to local and global stressors. This study focused on phytoplankton variations in relation to seasonal environmental changes on a multiannual time scale (2006–2015) at a Mediterranean eutrophic reservoir (Bidighinzu Lake, Italy) belonging to the Italian, European and International Long Term Ecological Research networks. Phytoplankton cell density, volume and biomass and chlorophyllaconcentrations were analysed together with meteo-climatic, hydrological, physical and chemical variables to detect trends and correlations. The period under study was also compared with previous years to assess the presence of significant differences in the environmental and planktonic compartments. Multiannual changes were more pronounced in summer than in the other seasons during the decade under study. The most conspicuous environmental changes were a significant decrease in summer nutrient concentrations in the reservoir and a simultaneous anthropic pressure reduction in the watershed. In addition, the mixing zone and euphotic zone ratio also increased. Multiannual changes in summer phytoplankton composition consisted of an increased density of smaller Bacillariophyceae and Cyanophyceae, which replaced larger species of the same phytoplankton classes. This resulted in opposite trends of total phytoplankton cell density (increasing) and mean phytoplankton cell volume (decreasing) over the study years. The nutrient decrement was statistically the strongest environmental driver of the phytoplankton changes observed in the reservoir. However, the mixing zone and the euphotic zone ratio and water temperature also significantly affected the multiannual phytoplankton variations. Therefore, we conclude that the success of small cell-sized phytoplankton in Bidighinzu Lake was most probably due to the synergic interactions of more environmental forces related to changing anthropic pressures and climate variability. Our results highlight the importance of long-term monitoring of reservoirs in the Mediterranean basin, especially in semi-arid regions where the need and scarcity of high quality water will be further exacerbated due to the global climate change.

Switch from production of subitaneous to delayed-hatching and diapause eggs in Acartia japonica Mori, 1940 (Copepoda: Calanoida) from Sagami Bay, Japan

To clarify temporal variation of in situ egg production of the copepods, Acartia japonica Mori, 1940, in Sagami Bay, central Japan, the species’ abundance, egg morphology and hatching patterns were studied during 2015. Adults of A. japonica were observed in the water column from June to October. Results showed that adults reared in the laboratory produced three types of eggs: subitaneous, delayed-hatching and diapause. All egg types had a surface covered with short spines; diapause eggs had a thicker chorion than subitaneous eggs. During the early period of the species occurrence in the bay, most females produced only subitaneous eggs, which hatched within 72 h. From the end of September, a large proportion of females began to produce diapause eggs. Linear regression analysis showed that the ratio of diapause eggs was negatively correlated with day length and water temperature (P < 0.05). Delayed-hatching eggs generally hatched over a broad time span and were also produced in conjunction with diapause eggs. This is the evidence that individual females of a marine copepod could produce all three-egg types simultaneously. Diapause eggs of A. japonica had the capacity to survive at least 300 days at ambient temperatures in the laboratory. The production of diapause eggs in this species probably functions to connect temporally separate populations in each year. Production of all three-egg types likely insures the species’ viability as a copepod that is well adapted to seasonal and sudden environmental changes.

Temperature and oxygen related ecophysiological traits of snow trout (Schizothorax richardsonii) are sensitive to seasonal changes in a Himalayan stream environment.

In this study, we investigated the seasonal changes in key eco-physiological traits of a wild population of snow trout, Schizothorax richardsonii from river Gola in the Indian Himalayan region over one year. Live specimens (5.8-31.4 g) were electro-fished from their natural habitat during representative months of four seasons with notable differences in water temperature, oxygen concentration and saturation. After 24-72 h of captive-acclimation, the fishes were examined for upper and lower critical thermal limits (CTmax and CTmin), incipient lethal oxygen thresholds (ILOC and ILOS), apparent routine and maximum oxygen consumption rates (MO2rout and MO2max), and blood haemoglobin-haematocrit. Across the seasons, mean CTmin and CTmax values ranged from ∼0 to 34.6 °C, suggesting a relatively wide acute thermal tolerance range for this predominantly cold-water fish. Changes in the habitat's thermal condition during winter to summer was reflected in the CTmin (∼0-2.4 °C) and CTmax (31.7-34.4 °C) estimates, while the highest thermal scope (CTmax-CTmin; 33.2 °C) was recorded in autumn. Concurrently, the incipient lethal hypoxia threshold observed in autumn (ILOS-2.6% and ILOC-0.19 mgO2/L) was significantly lower than the other three seasons, possibly linked to warm-acclimation. The reduction in blood haemoglobin-haematocrit levels during winter could limit the oxygen carrying capacity, with possible reciprocations in thermal tolerance and aerobic metabolism. Concerning body mass corrected oxygen consumption, the apparent MO2rout was found to increase in a temperature-dependent manner from 150.3 mgO2/kg/h at 12 °C to 315.2 mgO2/kg/h at 26 °C, with Q10 ranging from 1.6 to 2.2. Whereas, changes in MO2max was not temperature sensitive (Q10 of 0.7-1.3), except during spring-summer (Q10-2), with lowest and highest measurements in spring and autumn (934 and 1514 mgO2/kg/h), respectively. Collectively, these data form the first information report on the seasonal plasticity in thermal and respiratory physiology of a Schizothoracine fish species, bearing significance for their conservation, aquaculture and habitat monitoring.

Seasonal regulation of the lncRNA LDAIR modulates self-protective behaviours during the breeding season.

To cope with seasonal environmental changes, animals adapt their physiology and behaviour in response to photoperiod. However, the molecular mechanisms underlying these adaptive changes are not completely understood. Here, using genome-wide expression analysis, we show that an uncharacterized long noncoding RNA (lncRNA), LDAIR, is strongly regulated by photoperiod in Japanese medaka fish (Oryzias latipes). Numerous transcripts and signalling pathways are activated during the transition from short- to long-day conditions; however, LDAIR is one of the first genes to be induced and its expression shows a robust daily rhythm under long-day conditions. Transcriptome analysis of LDAIR knockout fish reveals that the LDAIR locus regulates a gene neighbourhood, including corticotropin releasing hormone receptor 2, which is involved in the stress response. Behavioural analysis of LDAIR knockout fish demonstrates that LDAIR affects self-protective behaviours under long-day conditions. Therefore, we propose that photoperiodic regulation of corticotropin releasing hormone receptor 2 by LDAIR modulates adaptive behaviours to seasonal environmental changes.

Non-invasive methods to measure inter-renal function in aquatic salamanders-correlating fecal corticosterone to the environmental and physiologic conditions of captive Necturus.

This study sought to develop non-invasive techniques to monitor glucocorticoids in captive Necturus as a means to correlate inter-renal gland function in relation to environmental and physiological changes. Six individually housed breeding pairs of captive Necturus beyeri were subjected to seasonal changes in water temperature (30°F temperature differential) to stimulate natural breeding, specifically spermatophore deposition and oviposition. An enzyme immunoassay was validated for the measurement of N. beyeri faecal corticosterone metabolites (fCMs) by exhibiting parallelism and accuracy to the standard curve. Longitudinal (December 2016-October 2017) assessment of fCM concentrations and pattern of excretion from samples collected from the six breeding pairs revealed a seasonal inter-renal effect with higher concentrations (P < 0.05) excreted during months (December-March) of the year associated with breeding activity and when water temperatures were lowest. Males from each pair produced spermatophores starting on 08 December 8 2016 and ending on 05 April 2017. Females from four of the six pairs went on to successfully oviposit eggs in mid-late April 2017. One clutch was fertile, and three were non-fertile. No differences (P > 0.05) were detected in fCM concentrations between pairs in which oviposition did or did not occur. In addition, a novel waterborne corticosterone metabolite (wCM) assay was validated to overcome challenges associated with faecal collection in a group-housed amphibian. An adrenocorticotropic hormone (ACTH) challenge performed in an adult male Necturus maculosus resulted in a 50-fold increase in wCM at 4h post-injection and marked the first demonstration of a waterborne inter-renal response to ACTH in Necturus. This study not only provides insight into inter-renal function in an aquatic salamander that exhibits marked reproductive seasonality but also confirms utility of fCM and wCM measurements as non-invasive means of assessment.

Seasonal pelage color change of two sympatric arboreal squirrel species in the subarctic region

Some mammal species exhibit pelage color change with seasonal molt. Seasonal molt and pelage color change are beneficial to thermoregulation and concealment, associated with seasonal environmental change. The Eurasian red squirrel Sciurus vulgaris Linnaeus, 1758 and the Siberian flying squirrel Pteromys volans (Linnaeus, 1758) are arboreal and sympatrically distributed in the subarctic northern Eurasian Continent and Sakhalin and Hokkaido islands. We expect that diurnal S. vulgaris may demonstrate more conspicuous difference between summer and winter pelages than nocturnal P. volans, because of its protective coloration in each season. To test this conjecture, we investigated their seasonal pelage color change. To diminish the effect of geographic variation in pelage color, we chose S. vulgaris orientis Thomas, 1906 and P. volans orii (Kuroda, 1921), which are endemic subspecies of Hokkaido Island, Japan. We used skin and stuffed specimens and frozen materials and categorized them into two pelage groups (summer and winter pelages) based on collection date. Pelage color characteristics were measured with a spectrophotometer for lightness, redness and yellowness. Countershading was examined by comparing dorsal and ventral lightness. Both subspecies showed lighter winter pelage than summer pelage, suggesting their greyish-white winter pelage was beneficial to concealment from predators during winter. As we expected, seasonal changes of redness and yellowness were more clearly recognized in S. vulgaris than in P. volans. As S. vulgaris is diurnal and vulnerable to attack by diurnal avian predators, reddish and yellowish pelage patterns may be important for concealment. Because it is nocturnal, P. volans may not need this reddish and yellowish pelage. Sciurus vulgaris also had a remarkably counter-shaded body, indicating that its body may reduce predation risk from daytime visual predators. Differences in seasonal pelage color change of these two arboreal squirrels may be caused by their different circadian rhythms.

Seasonal changes in foraminiferal assemblages along environmental gradients in Adventfjorden (West Spitsbergen)

Foraminifera are numerically abundant components of the benthic fauna; thus, they are very important compounds in glaciomarine environments. However, ongoing oceanographic changes may influence their distribution, abundances and diversity differently at different times of the year. In the present study, we aimed to assess seasonal environmental changes in an Arctic fjord (Adventfjorden, W Spitsbergen) and the structure and distribution of benthic foraminiferal assemblages during four seasons (January, May, August, November). The study revealed that the benthic foraminiferal assemblages in Adventfjorden are susceptible to environmental changes related to enhanced inflow of shelf-transformed water (STW). We distinguished three zones in the fjord: (1) the deeper outer part influenced by STW, with living specimens staying in the few uppermost layers of sediment, (2) the shallower interior influenced by freshwater outflows and high sediment load, resulting in the dominance of opportunistic glaciomarine taxa constantly buried in the sediment, and (3) the central part, where the seasonal variation in the foraminifera assemblage reflects the interplay between the influence of riverine inputs and STW. Our study also revealed that the presence of STW in Adventfjorden favours an early spring appearance of juvenile foraminifera; however, the majority of the specimens are later withered and do not contribute to the summer pool of mature individuals. On the other hand, the majority of the mature specimens can survive during the winter because of sufficient organic matter stocks and year-long ice-free conditions.

Rapid response of fossil tetraether lipids in lake sediments to seasonal environmental variables in a shallow lake in central China: Implications for the use of tetraether-based proxies

Bacterial branched and archaeal isoprenoid glycerol dialkyl glycerol tetraethers (brGDGTs and isoGDGTs, respectively) have become important tools for the paleoclimate reconstruction of lacustrine systems. However, it is still unclear how geochemical proxies based on GDGTs, particularly in lake surface sediments, respond to seasonal environmental changes in shallow water lakes, whose sediment cores are increasingly being used for paleoenvironmental reconstruction. In this study, we collected samples from the top 0–2 cm of sediments and water column suspended particulate matter (SPM) at a monthly interval from June 2015 to May 2016 in Lake Donghu, a shallow lake in central China. An updated liquid chromatography method was used to separate the 5- and 6-methyl brGDGTs. A remarkable difference between the lake sediments, SPM, and catchment soils suggested that microorganisms inhabiting the surface sediments contributed a significant proportion of isoGDGTs and brGDGTs to the GDGT pool in the lake sediments. We found a clear seasonality in the concentration and distribution of core lipid (CL) isoGDGTs and brGDGTs in the lake surface sediments, in contrast to the absence of seasonality in brGDGTs in mid-latitude soils reported by previous studies. The intact polar lipid/CL ratios for both isoGDGTs and brGDGTs in the lake surface sediments were significantly higher than those in SPM and catchment soils and were higher in the warm seasons than in winter. This collectively suggested that the turnover of brGDGTs in the lake sediments was faster than that in soils. Furthermore, the GDGT-0/Cren ratio for the lake sediments exhibited a negative correlation with dissolved oxygen in the water column. The cyclisation degree of C5-methylated brGDGTs (CBT5ME) was strongly related to water pH. Seasonal temperature variation clearly impacted the methylation degree of C6-methylated brGDGTs (MBT′6ME) but had no influence on C5-methylated brGDGTs (MBT′5ME), as opposed to the dependence of MBT′5ME on temperature in global soils, peatlands and African lakes. Due to the fast turnover rate and the sensitive response to seasonality, we suggest that the seasonal variation of fossil GDGTs in lake sediments should be considered when developing a calibration using fossil GDGTs in shallow-water lake surface sediments.

Morpho-regulation in diverse chicken feather formation: Integrating branching modules and sex hormone-dependent morpho-regulatory modules.

Many animals can change the size, shape, texture and color of their regenerated coats in response to different ages, sexes, or seasonal environmental changes. Here, we propose that the feather core branching morphogenesis module can be regulated by sex hormones or other environmental factors to change feather forms, textures or colors, thus generating a large spectrum of complexity for adaptation. We use sexual dimorphisms of the chicken to explore the role of hormones. A long-standing question is whether the sex-dependent feather morphologies are autonomously controlled by the male or female cell types, or extrinsically controlled and reversible. We have recently identified core feather branching molecular modules which control the anterior-posterior (bone morphogenetic orotein [BMP], Wnt gradient), medio-lateral (Retinoic signaling, Gremlin), and proximo-distal (Sprouty, BMP) patterning of feathers. We hypothesize that morpho-regulation, through quantitative modulation of existing parameters, can act on core branching modules to topologically tune the dimension of each parameter during morphogenesis and regeneration. Here, we explore the involvement of hormones in generating sexual dimorphisms using exogenously delivered hormones. Our strategy is to mimic male androgen levels by applying exogenous dihydrotestosterone and aromatase inhibitors to adult females and to mimic female estradiol levels by injecting exogenous estradiol to adult males. We also examine differentially expressed genes in the feathers of wildtype male and female chickens to identify potential downstream modifiers of feather morphogenesis. The data show male and female feather morphology and their color patterns can be modified extrinsically through molting and resetting the stem cell niche during regeneration.

Seasonal, annual, and inter-annual Spiniferites cyst production: a review of sediment trap studies

Despite the fact that dinoflagellate cysts of the diverse genus Spiniferites are abundant in coastal and estuarine sediments worldwide, little is known about patterns of their seasonal or annual production. In this paper we review previously published data on Spiniferites cyst fluxes from eight sediment trap time series in estuarine (the Strait of Georgia, Saanich Inlet, Hudson Bay, Omura Bay), coastal (the Santa Barbara Basin, the Arabian Sea), and offshore (off Cape Blanc) environments. This is the first study that provides detailed inter-site comparison of dinoflagellate cysts in sediment traps and analyzes seasonal, annual, and inter-annual cyst production from different geographic regions. We identified that cyst fluxes of all Spiniferites species at a given location increased or decreased simultaneously in all studied sediment trap records. This indicates that different Spiniferites species react in a similar way to local environmental triggers at each site. Average daily total cyst fluxes recorded in the sediment trap time series and in the dated surface sediment samples are greater in coastal and estuarine waters where marine primary productivity is higher. This implies that nutrient availability might be an important factor stimulating Spiniferites production. There is no uniform seasonal pattern in Spiniferites fluxes, but the timing of elevated total Spiniferites fluxes coincided with intervals of local seasonal environmental change at each site. Analyses of all sediment traps revealed that intervals with the highest total Spiniferites fluxes correspond to the timing and intensity of local environmental change at the sea-surface when waters had: minimal turbidity, some water column stability or stratification, availability of nutrients, and sea-ice free conditions. The multi-year trap data record considerable inter-annual variability in Spiniferites fluxes and seasonality when environmental conditions between the years varied. A combination of factors and specific environmental conditions are required to enhance Spiniferites cyst production in each region.