Reproductive measures and chick provisioning of Cory's Shearwater Calonectris diomedea borealis in the Azores

Capsule Timing of breeding influenced wing-length at fledging, and egg size may be an indicator of fledging weight and the amount of food received by chicks.

Aims To investigate chick growth, temporal patterns of chick food provisioning and the importance of indices of parental condition or quality, egg size and hatching date, to predict nestling body mass and wing-length at fledging, and compare breeding and chick feeding characteristics between colonies in the northeast Atlantic.

Methods A survey of Cory's Shearwater nests was carried out at Vila islet. A sample of 52 chicks, ringed and weighed at hatching, was selected to study chick growth and food provisioning.

Results Hatching success (51%) was much lower than fledging success (87%). Both hatching date and egg size contributed to explain wing-length at fledging, but hatching date, which was negatively correlated with wing-length at fledging, had the most important contribution (22%). There was some indication that egg size may explain variation in fledging weight and the amount of food received by chicks. Food delivery and feeding frequency of chicks varied throughout the chick development stage and three phases were distinguished: (1) 0–29 days, the highest feeding frequency values and a linear increase in food delivery; (2) 30–69 days, an oscillation in food delivery and medium feeding frequencies; (3) 70–90+ days, a sharp decrease in both food delivery and feeding frequency.

Conclusion Variation in food availability did not seem sufficient to override the overall importance of indices of parental quality in determining reproductive measures and chick provisioning. Breeding and feeding characteristics were similar between colonies in the northeast Atlantic, with variability in chick provisioning higher further south.     

A forceful upper jaw facilitates picking-based prey capture: biomechanics of feeding in a butterflyfish,Chaetodon trichrous

Biomechanical models of feeding mechanisms elucidate how animals capture food in the wild, which, in turn, expands our understanding of their fundamental trophic niche. However, little attention has been given to modeling the protrusible upper jaw apparatus that characterizes many teleost species. We expanded existing biomechanical models to include upper jaw forces using a generalist butterflyfish, Chaetodon trichrous (Chaetodontidae) that produces substantial upper jaw protrusion when feeding on midwater and benthic prey. Laboratory feeding trials for C. trichrous were recorded using high-speed digital imaging; from these sequences we quantified feeding performance parameters to use as inputs for the biomechanical model. According to the model outputs, the upper jaw makes a substantial contribution to the overall forces produced during mouth closing in C. trichrous. Thus, biomechanical models that only consider lower jaw closing forces will underestimate total bite force for this and likely other teleost species. We also quantified and subsequently modeled feeding events for C. trichrous consuming prey from the water column versus picking attached prey from the substrate to investigate whether there is a functional trade-off between prey capture modes. We found that individuals of C. trichrous alter their feeding behavior when consuming different prey types by changing the timing and magnitude of upper and lower jaw movements and that this behavioral modification will affect the forces produced by the jaws during prey capture by dynamically altering the lever mechanics of the jaws. In fact, the slower, lower magnitude movements produced during picking-based prey capture should produce a more forceful bite, which will facilitate feeding on benthic attached prey items, such as corals. Similarities between butterflyfishes and other teleost lineages that also employ picking-based prey capture suggest that a suite of key behavioral and morphological innovations enhances feeding success for benthic attached prey items.     

不同气味对虎皮鹦鹉取食行为影响

研究发现许多鸟类具有发育良好的嗅觉系统,但气味是否影响鸟类取食行为的研究报道较少。本研究开展了长尾林鸮（Strix uralensis）、金雕（Aquila chrysaetos）、家犬和家猫的粪便气味以及香水和香烟的气味对虎皮鹦鹉（Melopsittacus undulates）取食行为影响的比较研究。研究发现,虎皮鹦鹉在香水气味下的取食意图显著低于长尾林鸮粪便气味和无气味对照;在金雕粪便、猫粪便、香水及香烟气味下的取食频次显著低于无气味对照,同时香水及香烟气味下的取食频次显著低于长尾林鸮粪便气味,说明虎皮鹦鹉可能通过气味识别潜在的风险,进而调整取食行为。     

A neuronal network model of primary visual cortex explains spatial frequency selectivity

We address how spatial frequency selectivity arises in Macaque primary visual cortex (V1) by simulating V1 with a large-scale network model consisting of O(10⁴) excitatory and inhibitory integrate-and-fire neurons with realistic synaptic conductances. The new model introduces variability of the widths of subregions in V1 neuron receptive fields. As a consequence different model V1 neurons prefer different spatial frequencies. The model cortex has distributions of spatial frequency selectivity and of preference that resemble experimental findings from the real V1. Two main sources of spatial frequency selectivity in the model are the spatial arrangement of feedforward excitation, and cortical nonlinear suppression, a result of cortical inhibition. Action Editor: Jonathan D. Victor     

Experimental chronic low‐frequency resistance training produces skeletal muscle hypertrophy in the absence of muscle damage and metabolic stress markers

Volitional animal resistance training constitutes an important approach to modeling human resistance training. However, the lack of standardization protocol poses a frequent impediment to the production of skeletal muscle hypertrophy and the study of related physiological variables (i.e., cellular damage/inflammation or metabolic stress). Therefore, the purposes of the present study were: (1) to test whether a long‐term and low frequency experimental resistance training program is capable of producing absolute increases in muscle mass; (2) to examine whether cellular damage/inflammation or metabolic stress is involved in the process of hypertrophy. In order to test this hypothesis, animals were assigned to a sedentary control (C, n = 8) or a resistance trained group (RT, n = 7). Trained rats performed 2 exercise sessions per week (16 repetitions per day) during 12 weeks. Our results demonstrated that the resistance training strategy employed was capable of producing absolute mass gain in both soleus and plantaris muscles (12%, p < 0.05). Furthermore, muscle tumor necrosis factor (TNF‐α) protein expression (soleus muscle) was reduced by 24% (p < 0.01) in trained group when compared to sedentary one. Finally, serum creatine kinase (CK) activity and serum lactate concentrations were not affected in either group. Such information may have practical applications if reproduced in situations where skeletal muscle hypertrophy is desired but high mechanical stimuli of skeletal muscle and inflammation are not. Copyright © 2010 John Wiley & Sons, Ltd.     

Diversity and antimicrobial activity of endophytic fungi isolated from Nyctanthes arbor-tristis, a well-known medicinal plant of India

Endophytic fungi from Nyctanthes arbor-tristis were isolated and evaluated for their antimicrobial activity. A total of 19 endophytic fungi were isolated from 400 segments of healthy leaf and stem tissues of N. arbor-tristis. Eighteen endophytic fungi were obtained from leaf, while only ten from stem. Alternaria alternata had the highest colonization frequency (15.0%) in leaf, whereas Cladosporium cladosporioides ranked first in stem with a colonization frequency of 12%. The diversity and species richness were found higher in leaf tissues than in stem. The similarity indices between leaf and stem were 0.473 for Jaccard’s and 0.642 for the Sorenson index, respectively. Of 16, 12 (75%) endophytic fungal extracts showed antibacterial activity against either one or more pathogenic bacteria. The endophytic Nigrospora oryzae showed maximum inhibition against Shigella sp. and Pseudomonas aeruginosa. The leaf endophytes Colletotrichum dematium and Chaetomium globosum exhibited a broad range of anibacterial activity and were active against Shigella flexnii, Shigella boydii, Salmonella enteritidis, Salmonella paratyphi, and P. aeruginosa. Nine out of 16 (56.25%) endophytic fungi exhibited antifungal activity to one or more fungal pathogens. Colletotrichum dematium inhibited 55.87% of the radial growth of the phytopathogen Curvularia lunata. The antimicrobial activity of these endophytic microorganisms could be exploited in the biotechnological, medicinal, and agricultural industries.     

大肠杆菌编码区碱基片段的分析研究

对大肠杆菌1231个编码开始区域和1307个编码终止区域内的6碱基片段、4碱基片段和3碱基片段进行了统计,发现绝大多数4碱基和3碱基模式出现在盯对频率小于2的范围之内;在这两个区域中,出现最多的碱基片段是多聚A;编码开始区域和编码终止区域的碱基构成模式有明显区别;编码开始区域里GGA类的稀有片段恰恰是SD区域最偏好的碱基片段;以TAG或CTA构造的3碱基模式为编码开始区和编码终止区的禁用模式。     

Costs and Benefits of Mating in the Grasshopper Chorthippus parallelus (Caelifera: Acrididae)

Fitness consequences of different levels of mating benefits, viz., (1) virgin, (2) seldom mated, (3) free mating chances with the same male throughout the female's life span, and (4) free mating chances with three males always offered, were investigated in female meadow grasshoppers Chorthippus parallelus. No differences among the treatments were apparent in egg number per pod, total egg number per female, and hatching success of larvae. Seldom-mated females had offspring with the heaviest average larval dry weight. We did not find costs of mating in terms of reduced female longevity and residual dry weight between the treatments.     

Computational analysis of DNA photolyases using digital signal processing methods

Sun light energy is used by plants to trigger their growth and development. However, an increase of UV-B light may lead to DNA damage. DNA photolyases are enzymes that repair the cyclobutane pyridine dimer (CPD) and 6–4 photoproduct lesions formed through UV irradiation of DNA. Many aspects of the repair process are under intense scientific investigation but still poorly understood. Here we have computationally analysed DNA-photolyases using the resonant recognition model (RRM), a physico-mathematical approach based on digital signal processing methods. The RRM proposes that protein interactions represent the transfer of resonant electromagnetic energy between interacting molecules at the particular frequency. Within this study we have determined photolyases characteristic frequency, “hot spots” amino acids corresponding to the functional mutations and functional active/binding sites, and designed photolyase peptide analogous. A mutual relationship between photolyase and p53 tumour suppressor protein has also been investigated. The results obtained provide new insights into the structure–function relationships of photolyase protein family.