Pemeriksaan Kadar Residu Oksitetrasiklin Hidroklorida dan Tetrasiklin Hidroklorida dalam Udang Windu (Penaeus Monodon Fabricius) Pada Beberapa Lokasi Tambak Sidoarjo Secara KLT-Densitometri

Udang windu mempunyai nilai ekonomis yang lebih tinggi bila dibandingkan dengan jenis udang lainnya sehingga disamping untuk konsumsi dalam negeri udang windu mempunyai peranan penting dalam perolehan devisa negara. Untuk mencegah turunnya produksi udang windu yang salah satunya disebabkan oleh penyakit bakterial, petani tambak sering menggunakan antibiotika yang diberikan melalui pakan atau air tambak. Jika penggunaannya tidak tepat, dapat menyebabkan adanya residu antibiotika tersebut pada tubuh udang. Pada penelitian ini, sampel udang windu diambil dari tiga lokasi tambak di Sidoarjo berdasarkan jumlah produksi udang windu terbesar tiap tahunnya. Untuk analisis digunakan metode KlT-densitometri. Sebelum pemeriksaan sampel, terlebih dahulu dilakukan validasi metode dengan parameter selektifitas, linieritas, batas deteksi, batas kuantitasi, akurasi dan presisi. Pada penentuan kadar Oksitetrasiklin HCl dan Tetrasiklin HCl dalam udangwindu, metode yang digunakan telah memenuhi persyaratan validasi. Untuk selektifitas digunakan fase gerak kloroform : metanol : 5% Na2 EDTA ( 65 : 20 : 5), diambil lapisan bawah, Sedangkan persyaratan validasi lain untuk Oksitetrasiklin HCl diperoleh linieritas dengan harga r : 0,996676221 dan harga Vxo = 3,73%, batas deteksi = 0,0560 µg, batas kuantitasi : 0,1865 µg, akurasi : 90,90% dan presisi = 7,45%. Untuk Tetrasiklin HCl diperoleh linieritas dengan harga r : 0,999I 2758 7 dan Vxo = l,9l%, batas deteksi = 0,0286 µg, batas kuantitasi = 0,0954 µg, akurasi = 90,46% dan presisi: 6,76%. Hasil penclitian menunjukkan bahwa udang windu dari ketiga lokasi tambak di Sidoarjo tidak mengandung residu Oksitetrasiklin HCL tetapi mengandung residu Tetrasiklin HCL dengan kadar untuk lokasi tambak X = 90,7619 µg/g berat basah atau 412,7415 µg/g berat kering, lokasi tambak Y : 186,4332 pg/g berat basah atau 918,3899 µg/g berat kering, lokasi tambak Z : 279,4517 µg/g berat basah atau 13 54,58 86 µg/g berat kerin

Associative Retrieval Processes in Episodic Memory

Association and context constitute two of the central ideas in the history of episodic memory research. Following a brief discussion of the history of these ideas, we review data that demonstrate the complementary roles of temporal contiguity and semantic relatedness in determining the order in which subjects recall lists of items and the timing of their successive recalls. These analyses reveal that temporal contiguity effects persist over very long time scales, a result that challenges traditional psychological and neuroscientific models of association. The form of the temporal contiguity effect is conserved across all of the major recall tasks and even appears in item recognition when subjects respond with high confidence. The nearuniversal form of the contiguity effect and its appearance at diverse time scales is shown to place tight constraints on the major theories of association

Tissue-specific control of the endocycle by the anaphase promoting complex/cyclosome inhibitors UVI4 and DEL1

The endocycle represents a modified mitotic cell cycle that in plants is often coupled to cell enlargement and differentiation. Endocycle onset is controlled by activity of the Anaphase Promoting Complex/Cyclosome (APC/C), a multisubunit E3 ubiquitin ligase targeting cell-cycle factors for destruction. CELL CYCLE SWITCH52 (CCS52) proteins represent rate-limiting activator subunits of the APC/C. In Arabidopsis (Arabidopsis thaliana), mutations in either CCS52A1 or CCS52A2 activators result in a delayed endocycle onset, whereas their overexpression triggers increased DNA ploidy levels. Here, the relative contribution of the APC/C-CCS52A1 and APC/C-CCS52A2 complexes to different developmental processes was studied through analysis of their negative regulators, being the ULTRAVIOLET-B-INSENSITIVE4 protein and the DP-E2F-Like1 transcriptional repressor, respectively. Our data illustrate cooperative activity of the APC/C-CCS52A1 and APC/C-CCS52A2 complexes during root and trichome development, but functional interdependency during leaf development. Furthermore, we found APC/C-CCS52A1 activity to control CCS52A2 expression. We conclude that interdependency of CCS52A-controlled APC/C activity is controlled in a tissue-specific manner

F-Box protein FBX92 affects leaf size in Arabidopsis thaliana

F-box proteins are part of one of the largest families of regulatory proteins that play important roles in protein degradation. In plants, F-box proteins are functionally very diverse, and only a small subset has been characterized in detail. Here, we identified a novel F-box protein FBX92 as a repressor of leaf growth in Arabidopsis. Overexpression of AtFBX92 resulted in plants with smaller leaves than the wild type, whereas plants with reduced levels of AtFBX92 showed, in contrast, increased leaf growth by stimulating cell proliferation. Detailed cellular analysis suggested that AtFBX92 specifically affects the rate of cell division during early leaf development. This is supported by the increased expression levels of several cell cycle genes in plants with reduced AtFBX92 levels. Surprisingly, overexpression of the maize homologous gene ZmFBX92 in maize had no effect on plant growth, whereas ectopic expression in Arabidopsis increased leaf growth. Expression of a truncated form of AtFBX92 showed that the contrasting effects of ZmFBX92 and AtFBX92 gain of function in Arabidopsis are due to the absence of the F-box-associated domain in the ZmFBX92 gene. Our work reveals an additional player in the complex network that determines leaf size and lays the foundation for identifying putative substrates

The role of the frontal cortex in memory: an investigation of the Von Restorff effect

Evidence from neuropsychology and neuroimaging indicate that the pre-frontal cortex (PFC) plays an important role in human memory. Although frontal patients are able to form new memories, these memories appear qualitatively different from those of controls by lacking distinctiveness. Neuroimaging studies of memory indicate activation in the PFC under deep encoding conditions, and under conditions of semantic elaboration. Based on these results, we hypothesize that the PFC enhances memory by extracting differences and commonalities in the studied material. To test this hypothesis, we carried out an experimental investigation to test the relationship between the PFC-dependent factors and semantic factors associated with common and specific features of words. These experiments were performed using Free-Recall of word lists with healthy adults, exploiting the correlation between PFC function and fluid intelligence. As predicted, a correlation was found between fluid intelligence and the Von-Restorff effect (better memory for semantic isolates, e.g., isolate “cat” within category members of “fruit”). Moreover, memory for the semantic isolate was found to depend on the isolate's serial position. The isolate item tends to be recalled first, in comparison to non-isolates, suggesting that the process interacts with short term memory. These results are captured within a computational model of free recall, which includes a PFC mechanism that is sensitive to both commonality and distinctiveness, sustaining a trade-off between the two

Decoding the neural substrates of reward-related decision making with functional MRI

Although previous studies have implicated a diverse set of brain regions in reward-related decision making, it is not yet known which of these regions contain information that directly reflects a decision. Here, we measured brain activity using functional MRI in a group of subjects while they performed a simple reward-based decision-making task: probabilistic reversal-learning. We recorded brain activity from nine distinct regions of interest previously implicated in decision making and separated out local spatially distributed signals in each region from global differences in signal. Using a multivariate analysis approach, we determined the extent to which global and local signals could be used to decode subjects' subsequent behavioral choice, based on their brain activity on the preceding trial. We found that subjects' decisions could be decoded to a high level of accuracy on the basis of both local and global signals even before they were required to make a choice, and even before they knew which physical action would be required. Furthermore, the combined signals from three specific brain areas (anterior cingulate cortex, medial prefrontal cortex, and ventral striatum) were found to provide all of the information sufficient to decode subjects' decisions out of all of the regions we studied. These findings implicate a specific network of regions in encoding information relevant to subsequent behavioral choice

Reinstated episodic context guides sampling-based decisions for reward.

How does experience inform decisions? In episodic sampling, decisions are guided by a few episodic memories of past choices. This process can yield choice patterns similar to model-free reinforcement learning; however, samples can vary from trial to trial, causing decisions to vary. Here we show that context retrieved during episodic sampling can cause choice behavior to deviate sharply from the predictions of reinforcement learning. Specifically, we show that, when a given memory is sampled, choices (in the present) are influenced by the properties of other decisions made in the same context as the sampled event. This effect is mediated by fMRI measures of context retrieval on each trial, suggesting a mechanism whereby cues trigger retrieval of context, which then triggers retrieval of other decisions from that context. This result establishes a new avenue by which experience can guide choice and, as such, has broad implications for the study of decisions

Decoding information in the human hippocampus: a user's guide

Multi-voxel pattern analysis (MVPA), or 'decoding', of fMRI activity has gained popularity in the neuroimaging community in recent years. MVPA differs from standard fMRI analyses by focusing on whether information relating to specific stimuli is encoded in patterns of activity across multiple voxels. If a stimulus can be predicted, or decoded, solely from the pattern of fMRI activity, it must mean there is information about that stimulus represented in the brain region where the pattern across voxels was identified. This ability to examine the representation of information relating to specific stimuli (e.g., memories) in particular brain areas makes MVPA an especially suitable method for investigating memory representations in brain structures such as the hippocampus. This approach could open up new opportunities to examine hippocampal representations in terms of their content, and how they might change over time, with aging, and pathology. Here we consider published MVPA studies that specifically focused on the hippocampus, and use them to illustrate the kinds of novel questions that can be addressed using MVPA. We then discuss some of the conceptual and methodological challenges that can arise when implementing MVPA in this context. Overall, we hope to highlight the potential utility of MVPA, when appropriately deployed, and provide some initial guidance to those considering MVPA as a means to investigate the hippocampus

From lists of behaviour change techniques (BCTs) to structured hierarchies: comparison of two methods of developing a hierarchy of BCTs

Objectives Behaviour change technique (BCT) Taxonomy v1 is a hierarchically grouped, consensus-based taxonomy of 93 BCTs for reporting intervention content. To enhance the use and understanding of BCTs, the aims of the present study were to (1) quantitatively examine the ‘bottom-up’ hierarchical structure of Taxonomy v1, (2) identify whether BCTs can be reliably mapped to theoretical domains using a ‘top-down’ theoretically driven approach, and (3) identify any overlap between the ‘bottom-up’ and ‘top-down’ groupings. Methods and design The ‘bottom-up’ structure was examined for higher-order groupings using a dendrogram derived from hierarchical cluster analysis. For the theory-based ‘top-down’ structure, 18 experts sorted BCTs into 14 theoretical domains. Discriminant Content Validity was used to identify groupings, and chi-square tests and Pearson's residuals were used to examine the overlap between groupings. Results Behaviour change techniques relating to ‘Reward and Punishment’ and ‘Cues and Cue Responses’ were perceived as markedly different to other BCTs. Fifty-nine of the BCTs were reliably allocated to 12 of the 14 theoretical domains; 47 were significant and 12 were of borderline significance. Thirty-four of 208 ‘bottom-up’ × ‘top-down’ pairings showed greater overlap than expected by chance. However, only six combinations achieved satisfactory evidence of similarity. Conclusions The moderate overlap between the groupings indicates some tendency to implicitly conceptualize BCTs in terms of the same theoretical domains. Understanding the nature of the overlap will aid the conceptualization of BCTs in terms of theory and application. Further research into different methods of developing a hierarchical taxonomic structure of BCTs for international, interdisciplinary work is now required. Statement of contribution What is already known on this subject? * Behaviour change interventions are effective in improving health care and health outcomes